Who (pronoun)
The pronoun who, in English, is an interrogative pronoun and a relative pronoun, used primarily to refer to persons. Unmarked, "who" is the pronoun’s subjective form; its inflected forms are the objective "whom" and the possessive "whose". The set has derived indefinite forms "whoever", "whomever", and "whoseever," as well as a further, earlier such set "whosoever," "whomsoever", and "whosesoever" (see also "-ever"). Etymology. The interrogative and relative pronouns "who" derive from the Old English singular interrogative , and whose paradigm is set out below: It wasn't until the end of the 17th century that "who" became the  only pronoun that could ask about the identity of persons and "what" fully lost this ability. "The first occurrences of wh-relatives date from the twelfth century (with the possible exception (see Kivimaa 1966: 35)). The wh- form does not become frequent, however, until the fourteenth century." Notably, relative "whose" can still today refer to non-persons (e.g., "the car whose door won't open"). The spelling 'who' does not correspond to the word's pronunciation ; it is the spelling that represents the expected outcome of , while the pronunciation represents a divergent outcome – for details see Pronunciation of English ⟨wh⟩.  The word is cognate with Latin and Greek . Uses. As interrogative pronoun. "Who" and its derived forms can be used as interrogative pronouns, to form questions: The same forms (though not usually the emphatic ones) are used to make indirect questions: The corresponding form when referring to non-humans is "what" (which has the emphatic form "whatever", and no possessive form). Another similar interrogative is "which" – this can refer to either humans or non-humans, normally implying selection from a particular set, as either interrogative pronoun ("Which do you prefer?") or interrogative determiner (adjective) ("Which man should I choose?"). 'What ' can also be used as a determiner ("What book are you reading?"), but 'who' cannot. "Which", "who", and "what" as interrogatives can be either singular or plural; (examples including, "Which is the highest hill?" "Which are the highest hills?" "Who was born in 1920?" "Who were king and queen in 1920?") however, "who" and "what" often take a singular verb regardless of any supposed number. The questions "Who wants some cake?" and "What's in the bag?" do not presuppose anything about number in possible responses: "I want some cake", or "All of us want some"; and "A rabbit  is in the bag", or "Five coins and a bus ticket". As relative pronoun. The other chief use of "who" and its derivatives are in the formation of relative clauses: The corresponding form for non-humans is "which", although "whose" can be used as a possessive in relative clauses even when referring to non-humans: "I will have to fix the car whose engine I ruined." In restrictive relative clauses, when not preceded by a preposition, both "who(m)" and "which" can be replaced by "that", or (if not the subject of the clause) by zero. In relative clauses, "who" (like  other relative pronouns) takes the number (singular or plural) of its antecedent. "Who" also takes the person (first, second or third) of its antecedent: "Who" and "whom" can also be used to form free relative clauses (those with no antecedent). The emphatic forms are often used for this purpose: informal: "I'll take whoever you choose"; formal: "I'll take whomever/whomsoever you choose". This corresponds to the use of "what(ever)" when referring to non-humans. (For the choice between "who(ever)" and "whom(ever)" in formal English, see below.) The emphatic forms can also be used to make adverbial clauses, as  in "Whomever/Whoever you choose, I'll be satisfied". For more details, see English relative clauses. Usage of "whom". Tendency to replace "whom" with "who". According to traditional prescriptive grammar, "who" is the subjective (nominative) form only, while "whom" is the corresponding objective form (just as "him" is the objective form corresponding to "he"). However, it has long been common, particularly in informal English, for the uninflected form "who" to be used in both cases, thus replacing "whom" in the contexts where the latter was traditionally used. In 1975, S. Potter noted in "Changing English" that, "nearly half a century  ago Edward Sapir predicted the demise of "whom", showing at great length that it was doomed because it was 'psychologically isolated' from the objective pronouns me, us, him, her, them on the one hand, and the invariables which, what, that and where, when, how, why on the other." By 1978, the 'who'–'whom' distinction was identified as having "slipped so badly that [it is] almost totally uninformative". According to the OED (2nd edition, 1989), "whom" is "no longer current in natural colloquial speech". Lasnik and Sobin argue that surviving occurrences of "whom" are not part of ordinary English grammar, but the  result of extra-grammatical rules for producing "prestige" forms. According to Mair, the decline of "whom" has been hastened by the fact that it is one of relatively few synthetic (inflected) remnants in the principally analytical grammar of Modern English. It has also been claimed that the decline of "whom" is more advanced in the interrogative case than in the relative case, this possibly being related to the degree of complexity of the syntax. However, some prescriptivists continue to defend "whom" as the only "correct" form in functions other than the subject. Mair notes that: "'whom' is moribund as an  element of the core grammar of English, but is very much alive as a style marker whose correct use is acquired in the educational system [, where it is taught]. [The use of "whom"] is highly restricted, but rather than disappear entirely, the form is likely to remain in use for some time to come because of its overt prestige in writing." "Whom is also sometimes used by way of hypercorrection, in places where it would not even be considered correct according to traditional rules, as in "Whom do you think you are?" For more examples see the section below. Retention  of the 'who'–'whom' distinction often co-occurs with another stylistic marker of formal or "prestige" Englishavoidance of the stranded preposition. This means that "whom" can frequently be found following a preposition, in cases where the usual informal equivalent would use "who" and place the preposition later in the sentence. For example: In relative clauses, movement of the preposition further allows "who" to be replaced by "that" or removed entirely: Usage of "who" and "whom". In the types of English in which "whom" is used (which are generally the more formal varieties, as described in the section above), the general grammatical  rule is that "who" is the subjective (nominative) form, analogous to the personal pronouns "I", "he", "she", "we", "they", while "whom" is the objective (oblique) form, analogous to "me", "him", "her", "us" and "them". Thus, "who" is used as a verb subject, while "whom" is used as an indirect or direct object of a verb or as the object (complement) of a preposition. Examples: Notice that in a relative clause, the form depends on the role of the pronoun in the relative clause, not that of its antecedent in the main clause. For example, "I saw the man who ate  the pie"not "whom", since "who" is the subject of "ate" (original sentence, before being changed to a clause: "'He' ate the pie"); it makes no difference that its antecedent "(the) man" is the object of "saw". In the position of predicative expression, i.e. as the complement of forms of the copula "be", the form "who" is used, and considered correct, rather than "whom". (Compare the case of the personal pronouns, where the subjective form is traditionally considered correct, although the objective forms are more commonly usedsee .) In the examples that follow, notice how, when the verb is a form of  be, the question "Who is the captain of the team?" or the noun clause "who the captain of the team is" (we know it is a noun clause because it replaces the word "something") is the same regardless of whether the original placement of the unknown person was before or after "be" (is): Ambiguous cases. A problem sometimes arises in constructions like this: Use of "who" here is normal, and to replace it with 'whom' would be grammatically incorrect, since the pronoun is the subject of "was", not the object of "say". (One would write "You say [that] 'he' [not  'him'] was a great composer".) Nevertheless, "whom" is quite commonly encountered, and even defended, in sentences of this type. It may arise from confusion with a form like: In this case, "whom" is used correctly according to the traditional rules, since it is now the object of the verb "believe". (One would write "You believe him [not 'he'] (to be) a great composer.") The use of "whom" in sentences of the first type ("Beethoven, whom you say was a great composer...")referred to as "subject 'whom' can therefore be regarded as a hypercorrection, resulting from awareness of a perceived need  to correct "who" to "whom" in sentences of the second type. Examples of this apparently ungrammatical usage can be found throughout the history of English. The "OED" traces it back to the 15thcentury, while Jespersen cites even earlier examples from Chaucer. More examples are given below: Doubts can also arise in the case of free relative clauses, formed with "who(m)", "who(m)ever" or "who(m)soever". Modern guides to English usage say that the relative pronoun should take the case appropriate to the relative clause, not the function performed by that clause within an external clause. For example, it is correct to write  I'll talk to whoever [not "whomever"] "will listen", since "whoever" is the subject of "will listen" (regardless of the fact that the entire clause "whoever will listen" serves as the object of the preposition "to"). On the other hand, "Whomever you choose will suit me" is correct, since "whomever" is now the object of "choose" (despite the fact that the entire relative clause is the subject of "will suit"). Similarly: In sentences of this type, however, as with the "subject "whom"" examples above, use of "whom(ever)" is sometimes found in places where it would not be expected grammatically, due  to the relative complexity of the syntax. In fact in Middle English it was standard for the form of the pronoun to depend on the function in the external clause; the modern rule came about through re-analysis of the pronoun as primarily an element of the internal clause. Usage of "whose". "Whose" is the genitive case of "who". Unlike the other forms of "who", relative "whose" (but not interrogative "whose") can still refer to non-persons, in the way that all forms of the word could in Old and Middle English.