# Linguistics/Semantics

Semantics is the study of meaning. There are two types of meaning: conceptual meaning and associative meaning. The conceptual meaning of the word sea is something that is large, filled with saltwater, and so on. This meaning is true for everyone. The associative meaning might be pirates, shipwreck, storms, battle and so on. These associations vary from person to person. The conceptual meaning of concise is expressed in few words, but concise being a good thing is part of the associative meaning.

## Reference and Sense

Reference refers to what an expression refers to in the real world. For example, Wikibooks refers to the website where you can find this book. Barack Obama refers to the first black president of the United States. In the sentence Jimmy Wales, who founded Wikipedia, is an intelligent man, who refers to Jimmy Wales.
Constant reference occurs when an expression always refers to the same thing, regardless of context. The Democratic People's Republic of Korea usually has constant reference, as does Noam Chomsky. Smith, Mary and the dog do not have constant reference.
Sense is different from reference in that sense does not take care of objects in the real world. When you look in a dictionary, most of the definitions you get tell you the senses of the words. Consider this extract from Wiktionary's entry on plane:
* An airplane; an aeroplane.
* A level or flat surface.
* A level of existence or development.
None of these are related to actual aeroplanes or surfaces in the real world. They are senses.

## Semantic Features

To express meaning, we use semantic features. For example, castle is something that with the features [+large, +building, +fortified]. A house that is easy to attack wouldn't be a castle because it does not necessarily have the [+fortified] feature. We can even list semantic features as a table:
| | large | building | fortified |
| castle | + | + | + |
| palace | + | + | - |
| planet | + | - | - |
| fort | - | + | + |
Sometimes, a sentence is syntactically correct, but semantically meaningless. Let's revisit Chomsky's example:
(1a) Colourless green ideas sleep furiously.
Obviously, this sentence doesn't make sense to us at all. We can often determine what words can fit into a sentence by using semantic features. Consider this example:
(1b) The N[+living] was killed.
This would prevent us from saying 'the homework was killed' or 'the building was killed'.

## Lexical Relations

A lexical relation is the relationships between the meanings of words. Here are some important lexical relations:
* Homophony: When two words have the same pronunciation, but are written differently and mean different things, such as bare and bear.
* Homonymy: When two words have the same pronunciation and spelling, but mean different things, such as the verb bear and the noun bear.
* Polysemy: When a single word has multiple meanings. For example, the verb bear can mean tolerate, but also bring (he bore gifts) or have (they bear a certain resemblance).
* Synonymy: When two words are close in meaning, such as the synonyms insinuate and suggest. Although they are similar, they are not identical.
* Antonymy: When two words have opposite meanings, such as the unmarked pair of antonyms happy and sad or the marked pair of antonyms unhappy and happy. There are two types of antonyms:
** Gradable antonyms: These are words with various degrees, such as happy and sad. Not happy is not the same as sad.
** Non-gradable antonyms: These are words without degrees; it's either one way or the other, such as on and off. Your computer is either one or the other: it is not on indicates it is off.
*** Reversives: Sometimes, with a pair of antonyms X and Y, not X does not imply Y. For example, I did not close the windows does not imply I opened the windows. These are reversives.
** Converse or Reciprocal antonym: If A happened before B, then B must have happened after A. If A is B's parent, then B is A's child. This relationship is called converse.
* Hyponymy: When one word indicates a category of things that is a subset of the category of things indicated by another word. For example, child is a hyponym of human, which is a superordinate of child. Child and adult are called cohyponyms.
** Prototype: Sometimes, a certain hyponym is more representative of the superordinate than most. For example, when you hear the word 'fish', you probably don't think about weird fish like seahorses or swordfish. You are more likely to think of, say, salmon, which is said to be the prototype of the hyponymy.
* Metonymy: When a word is used in place of another related word. For example, you can say he found solace in the bottle if you want to express the idea that he drank alcohol to comfort himself. Using bottle instead of alcohol is metonymy.
** Synecdoche: It is a type of metonymy when you're substituting a word for a part of it, e.g. farm hands.
* Metaphor: When a word is replaced with another because of similar attributes. For example, the Chinese word for communication, goutong, originally meant 'to merge two river channels into one by dreding'.
* Transferred epithet: It is when a word, usually an adjective, describes another word, but actually describes a third concept. For example, happy in a happy morning describes not the morning, but the mood of the speaker during the morning.
* Collocation: When two words go well with each other, such as deliver and speech, formulate and policy, and interesting and proposition. These are found by looking at statistics in a corpus, or a collection of language in use.

## Semantic Roles

The role played by a word in expressing meaning is called the semantic role or thematic role. Here are some common ones:
* Agent: The 'doer' of an action, like the cat in The cat scratched the sofa.
* Theme or Patient: The 'receiver' of the action, like the sofa in The cat scratched the sofa.
* Experiencer: Someone or something that 'experiences' the situation, like the child in The child saw the cat scratching the sofa.
* Instrument: Something that the agent uses to do something, like its paws in The cat scratched the sofa with its paws.
* Recipient: Something or someone that receives something, like the cat in The child gave the cat its food.
* Time: Surprisingly enough, that is the time when an action is done, such as midnight in The cat scratch the sofa at midnight.

## Propositions

A proposition is something that can either be true or false. Consider these examples:
(2a) Xi Jinping is the paramount leader of China. (2b) Tomatoes are blood-sucking mammoths. (2c) Is Wikibooks a city in Canada? (2d) Get out of my house!
All of these are propositions. The first two are statements in which the truth value of the propositions are asserted to be true, although the speaker of (2b) was clearly mistaken. The third and fourth are a question and a command respectively; they are both propositions, even though the speaker did not assert their truth values.
These sentences both express the same proposition:
(3a) Roses have thorns. (3b) Plants of the genus rosa possess spinose structures.
Even though the sentences are different, the proposition is the same: it is the proposition which is true if roses indeed have thorns.