Romanian nouns, under the rules of Romanian grammar, are declined, varying by gender, number, and case.
 An intrinsic property of Romanian nouns, as in all Romance languages, is their gender. However, while most Romance languages have only two genders, masculine and feminine, Romanian also has neuter gender. In Latin, the neuter is a separate gender, requiring all determiners to have three distinct forms, such as the adjective bona, bonus, bonum (meaning good). Comparatively, Romanian neuter is a combination of the other two genders. More specifically, in Romanian, neuter nouns behave in the singular as masculine nouns and in the plural as feminine nouns. As such, all noun determiners and all pronouns only have two possible gender-specific forms instead of three. From this perspective, it's possible to say that in Romanian there are really just two genders, masculine and feminine, and the category labeled as neuter contains nouns whose gender switches with the number. This class of neuter nouns are also known as eterogene or 'heterogenous', as ambigene meaning 'ambigenous' or 'of both kinds ,' or mixed nouns.
 Depending on gender, otherwise similar nouns will inflect differently. For example, the nouns "câine" (dog, compare Latin canis) and "pâine" (bread, compare Latin panis) have phonetically identical endings in the main form (nominative singular), but the former is a masculine noun, while the latter is feminine. For this reason, when inflected they behave in very different manners:
 Also, the gender of a noun determines the morphology of most determiners, such as articles, adjectives, demonstratives, numerals. The two nouns taken as examples above will give:
 While in many cases assigning the correct gender may be facilitated by the noun ending or meaning, the distinction is usually difficult for those learning Romanian as a second language. For natives, the one-two test is practically infallible: Saying "un câine - doi câini" makes it clear, by the form of the determining numerals, that "câine" is masculine. When the numerals take the forms "o ... - două ..." the noun in question is feminine, and finally the forms "un ... - două ..." are indicative of a neuter noun.
 The following phonetic rules can be used, to some degree, to infer the grammatical gender for nouns when these are in their nominative singular form, and without any determiner that could help in recognizing the gender.
 These rules can be further refined when the noun is recognized as being derived from other words by use of specific endings, as follows:
 Rules other than phonetic can be used when the meaning of the noun is known or at least its semantic group is recognized. In this category obvious examples are proper names of people, or nouns designating nationality, profession, etc. Nouns referring to animals and birds are always specific to their biological gender, and often occur in pairs the same way as we have cow and bull in English. Less obvious situations are described below.
 Like all Indo-European languages, Romanian differentiates morphologically the singular and the plural number of nouns. Within the Romance languages, regarding the plural formation, Romanian falls in the group East from the La Spezia–Rimini Line together with Italian. As such, the plural is formed by the addition or change of the final vowel of the singular noun, very often accompanied by other vocalic and/or consonantic shifts in the noun stem, consonant deletion, and/or the interposition of other phonemes. Occasionally, the plural noun has the same form as the singular. A few nouns are defective by missing either the singular or the plural. Finally, some nouns can form the plural in several ways, depending on the meaning. To illustrate, here are just a few examples:
 Most Romanian plural nouns, in their nominative non-articulated forms, end in "i" with another large category ending in "e". Only some recent borrowings make up the very few exceptions to this rule, which seems to be a very stable feature of the language. Among the old Romanian nouns the only exception is "ou" /ˈow/ (egg), which makes the plural "ouă" /ˈowə/.
 Morphologically, the plural is built by using one of the following four endings: -i, -uri, -e, and -(e)le. Of these, the last one used to have few representatives, such as "stea" - "stele" (star) and "nuia" - "nuiele" (wicker). Subsequent borrowings enlarged this group, in particular a series of nouns from Turkish ending in stressed "a" which were assigned to the feminine gender (although Turkish nouns do not have gender).
 Like the gender, the plural formation is an intrinsic property of the noun, and is acquired by native speakers one by one together with the respective noun. The tables below show the plural formation modes for nouns according to their gender, in the non-articulated nominative/accusative case. The asterisk (*) indicates irregular plural formation, requiring the insertion of consonants belonging neither to the stem nor to the plural ending, the deletion of stem consonants, or some unusual vocalic shifts.
 In writing, all masculine nouns and part of the feminine and neuter nouns end in letter "i" in the plural. However, this letter can correspond phonetically to either vowel /i/, semivowel /j/, or non-syllabic /ʲ/ (see Romanian phonology). The exact pronunciation depends on the preceding phonemes:
 The plural ending "e" is always a vowel and does not represent a pronunciation problem.
 Despite many plural endings changing the number of syllables in the nouns, the word stress does not generally shift. The only exceptions are a few irregular nouns such as: "soră" /ˈsorə/ - "surori" /suˈrorʲ/ (sister) and, "noră" /ˈnorə/ - "nurori" /nuˈrorʲ/ (daughter-in-law).
 Syntactically, Romanian nouns can be in any of five grammatical cases:
 The short definitions above are only an approximate indication of the actual usage. Here are some examples with the noun "băiat" (boy) in the various cases:
 Indefinite article (a, an, some)
 Morphologically, the five cases are expressed by giving the nouns three different forms. The nominative and the accusative share the same form, the distinction being made from the context, word order, or by the use of particular prepositions. Similarly, the genitive and the dative share the same form, distinguished syntactically or by the presence of possession articles when the nouns are in the genitive case. The vocative is less used than the other four, because it is limited to people, animals, or other things that can be addressed.
 Comparatively, other Romance languages, although maintaining a syntactic distinction between cases, have reduced them to a single form and replaced morphological variation with the use of specific prepositions. Latin used to have up to seven cases, the Romanian five plus the ablative and the locative.
 The case mark is always applied to the article, definite or indefinite, that determines the noun, and sometimes also to the noun itself. The indefinite article, like its English counterpart, is placed before the noun as a separate word, and has in Romanian different forms for the nominative/accusative and for the genitive/dative (the vocative cannot be determined by an indefinite article). On the other hand, the Romanian definite article is always appended as an ending (see enclitic). As the plural mark and the case mark are attached also at the end of the word, the declension becomes a complex process of combining all three endings: The definite article has special forms for the various cases and numbers, and is placed after the plural mark with possible phonetic changes to make the word easily pronounceable.
 The table below gives the complete paradigm of the masculine noun "bou" (ox).
 The general rule for the declension of nouns when they are accompanied by the indefinite article is that the article changes form and the noun keeps its main (nominative) form at all cases. The only exception is the singular of feminine nouns in the genitive/dative forms: they use their respective plural nominative forms in addition to inflecting the indefinite article. The tables below give a few examples. Three nouns from each gender were chosen as representatives:
 In the singular, in the nominative/accusative case, the definite article is -(u)l or -le for masculine and neuter nouns and (u)a for feminine nouns. When these forms are changed for the genitive/dative case, the definite article becomes -lui for masculine and neuter nouns and -i for feminine. To obtain these forms, the definite article for masculine and neuter simply affix the ending -ui after consonant l (after removing vowel e where it exists). In the case of feminine nouns, the genitive/dative is derived not from the singular but from the plural non-articulated forms, by adding a semivocalic -i at the end.
 In the plural, in the nominative/accusative case, the definite article is -ii /iǐ/ for masculine nouns, and -le for neuter and feminine nouns. To put these forms into genitive/dative the masculine definite article is changed into -ilor, and the neuter and feminine definite article is changed into -lor.
 Nouns with definite article can also be in the vocative case. In the singular, nouns are either left in their nominative/accusative forms, or given the endings specific to gender: -le for masculine and neuter nouns, and -o for feminine nouns.
 The tables below show examples using the same nouns as previously.
 For the vocative, the square brackets are used where the respective forms can be imagined, but are not normally used. Additionally, some nouns can have two versions of vocative which can express slightly different attitudes toward the person (animal, thing, etc.) that is being addressed. For example, "iubit" (lover) has two vocative forms: "iubite" and "iubitule". The first sounds more direct and might be found in poems and song lyrics (Oh, my darling!), while the second sounds more natural in everyday life (Honey!) (Compare "my dear" in English which normally expresses close intimacy but is reduced to a mere formality when followed by the person's name: 'My dear Mr Smith').
 The genitive/dative forms require a special mention in the case of proper nouns representing people's names. For men's names, the inflection is replaced by placing the article lui before the noun, as a separate word.
 The same construction is sometimes applied to women's names, but the practice is considered by prescriptive grammar as incorrect, with the exception of feminine proper nouns that have a masculine-like ending:
 For proper nouns other than those referring to people, the genitive is constructed by inflection, like the common nouns.
 The following subsections describe the usage of each case.
 Nominative is the case of the subject and of the predicate nominal. Here are some examples:
 Genitive usually indicates possession or belonging, but is also used to show origin and others kinds of relationship. Additionally, while most prepositions require the noun they determine to take the accusative, there are some exceptions in which the genitive (or the dative) is required.
 The genitive is most often used in the pattern noun for possessed + noun for possessor, with the noun denoting the possessor in the genitive case, like for example "balonul copilului" means child's balloon (lit. the balloon of the child). In such a construction, if the possessed ("balonul", the balloon) has the definite article attached to it—the most usual situation—and the possessor ("copilului", of the child) comes immediately after, no other words are necessary to express the genitival relationship.
 In any other construction involving the genitive, a possessive article must be used, corresponding roughly to the English "of the". This can happen (1) when the possessed has the indefinite article, (2) when other words intervene between the two parts, or (3) when the possessed and possessor switch order in the sentence. The possessive article must agree in number and gender with the possessed, and has the forms below.
 Some prepositions and preposition compounds require the noun they determine to be in the genitive case. Examples:
 Nouns in the genitive can occur in series, as in "culoarea jucăriei copilului prietenului meu" (my friend's child's toy's color), but as in English more than three successive nouns become difficult to understand and are considered bad use of the language.
 The dative is used for the indirect object, that is, the noun representing the person/object that receives the action indicated by the verb. The dative is required by a particular series of verbs, many of which express the general idea of giving, hence the name. Examples:
 As in the examples above, the dative noun in such constructions is almost always doubled by a personal pronoun, itself in the dative case, which is placed near the verb no matter where the noun is in the sentence. Although not including this logically redundant pronoun does not affect the meaning and still produces grammatically correct sentences, native speakers seldom fail to include it. Depending on the verb mood, tense, and initial phoneme, the doubling personal pronoun will change in several regards: (1) which form, full or clitic, of the pronoun is used, (2) the position relative to the verb or verb parts, and (3) whether it is a true clitic attached phonetically to the verb or it is a separate word.
 The table below shows these patterns on two verb examples—one starting with a consonant and the other with a vowel—, "a da" (to give) and "a arăta" (to show). For personal moods only the first person in the singular is shown, as the other forms behave identically. In each table cell, the upper example is for the singular of the personal pronoun, and the lower one for the plural. In all situations the pronoun has the same form for all genders and only changes with number.
 As the examples show, when the verb is simple (not compound), the doubling pronoun is placed before the verb and has its full form. Exception to this rule make the imperative and the gerund, which require the clitic form bound at the end of the verb. Also, the past participle and the supine do not require the clitic doubling at all. When the verb is compound and includes the conjunction "să" (approximately equivalent to English to) or the infinitive preposition "a", the doubling pronoun is placed immediately after "să" / "a" and takes the clitic form in the singular ("să-i" and "a-i") and the full form in the plural ("să le" and "a le"). In all remaining situations the pronoun is placed before the first element of the compound verb and takes the clitic form, as in "i-am dat" and "le-am dat".
 When the verb starts with a vowel and the doubling pronoun comes right before it the use of the full or clitic is optional. In such cases the shorter (clitic) version one is more frequent in speech and informal writing.
 The gerund deserves a special mention, as not only is the doubling pronoun placed after the verb, but the verb itself receives an epenthetic "u". This "u" can be alikened to the vowels that take this position in the Latin gerund, and has become the Italian "o" as in "sto facendo" (I am doing).
 When the full doubling pronoun "îi" is placed before the verb (all parts of the verb, if compound), it can turn into its clitic form if it binds through elision to the word before it, as in "nu-i dau" (I don't give him), "că-i dau" (that I give him), "și-i dau" (and I give him).
 The imperative mood builds its affirmative and negative forms on different patterns, so that the position of the doubling pronoun is different. Compare "dă-i" → "nu-i da", "dă-le" → "nu le da".
 In poetry, archaic or regional speech, or invectives, the order of the compound verb elements can switch, and with them the position of the doubling pronoun will change. Compare: "i-am dat" → "datu-i-am", "le-am dat" → "datu-le-am", "le-aș da" → "da-le-aș". Note also the use of the epenthetic "u" again where otherwise a consonant would come just before the pronoun.
 Things are further complicated if another pronoun is present which claims a position near the verb, such as the pronoun that replaces or doubles the direct object. Here are some examples of how such situations are handled.
 Depending on the gender of the direct object, the pronoun position can be different in certain cases:
 If two pronouns having identical forms meet, the pronoun doubling the indirect object drops, as it is optional:
 Although most prepositions require the noun they determine to be in the accusative case, a few must be followed by a noun in the dative. Similarly, the dative is required by some adjectives, many of which conveying the general idea of being (or not) beneficial, or having derived from verbs that themselves require the dative. A few adverbs showing comparison fall into the same category. Examples:
 Depending on the sentence syntax, the adverbs above can also work as adjectives, nevertheless requiring the dative.
 The accusative is mainly the case of the direct object, but other nouns can take the accusative form: those indirect objects which aren't in the dative case, as well as most circumstantials and attributes built with prepositions. Examples:
 A particularity of Romanian is that the direct object is marked in certain situations by the preposition pe, which in such constructions loses its original meaning (on, above). The usage rules for this marker are complex and insufficiently codified; both semantics and morphology comes into play. Examples of direct object with marker "pe" are given below.
 The same preposition pe is used not only with nouns in accusative, but also with other words having the role of the direct object: pronouns (personal, interrogative, relative, demonstrative, indefinite or negative), numerals acting as pronouns, etc.
 As the vocative case gives the noun a distinct charge of familiarity, directness, and immediateness, nouns in the vocative are rarely used alone, except when addressing or calling someone. Most of the time, and particularly in writing, such nouns are used together with specific adjectives such as drag (dear) and stimat (respected, dear). Also, such adjective+noun constructions often include a possessive pronoun. Examples: