Antecedent (grammar)

In grammar, an antecedent (Etymology: Latin "antecedentem" meaning precede, a noun coming from "ante" - before, and the verb "cedere" - to go) is an expression (word, phrase, clause, sentence, etc.) that gives its meaning to a proform (pronoun, pro-verb, pro-adverb, etc.). A proform takes its meaning 
from its antecedent; e.g., "John arrived late because traffic held him up." The pronoun "him" refers to and takes its meaning from "John", so "John" is the antecedent of "him". Proforms usually follow their antecedents, but sometimes they precede them, in which case one is, technically, dealing with postcedents instead of antecedents. The prefix "ante-" means "before" or "in front of", and "post-" means "after" or "behind". The term "antecedent" stems from traditional grammar. The linguistic term that is closely related to "antecedent" and "proform" is "anaphora". Theories of syntax explore the distinction between antecedents and postcedents in terms of binding.
Examples.
Almost any syntactic category can serve as the antecedent to a proform. The following examples illustrate a range of proforms and their antecedents. The proforms are in bold, and their antecedents are underlined
This list of proforms and the types of antecedents that they take is by no means exhaustive, but rather it is intended to merely deliver an impression of the breadth of expressions that can function as proforms and antecedents. While the stereotypical proform is a pronoun and the stereotypical antecedent a noun or noun phrase, these examples demonstrate that most any syntactic category can in fact serve as an antecedent to a proform, whereby the proforms themselves are a diverse bunch. The last two examples are particularly interesting, because they show that some proforms can even take discontinuous word combinations as antecedents, i.e. the antecedents are constituents. A particularly frequent type of proform occurs in relative clauses. Many relative clauses contain a relative pronoun, and these relative pronouns have an antecedent. Sentences d and h above contain relative clauses; the proforms "when" and "which" are relative proforms.
Uncertain antecedents.
In some cases, the wording could have an uncertain antecedent, where the antecedent of a pronoun is not clear because two or more prior nouns or phrases could match the count, gender, or logic as a prior reference.
In such cases, scholars have recommended to rewrite the sentence structure to be more specific, or repeat the words of the antecedent rather than use only a pronoun phrase, as a technique to resolve the uncertain antecedent.
For example, consider the sentence, "There was a doll inside the box, which was made of clay" where the word "which" could refer to either the box or the doll. To improve, the sentence could be reworded as: "Inside the box, there was a doll which was made of clay" or, "Inside the box, there was a doll made of clay" or, "There was a girl doll inside the box, and she was made of clay" (or similar wording).
Antecedents may also be unclear when they occur far from the noun or phrase they refer to. Bryan Garner calls these, "remote relatives", and gives this example from the New York Times:
and points out that ""[t]hat" modifies "messages" — 7 words and 3 nouns before." He also give examples for "in which", "who", and "whose".
Postcedents.
The "ante-" in "antecedent" means 'before, in front of'. Thus when a proform precedes its antecedent, the antecedent is technically not an antecedent, but rather it is a postcedent, "post-" meaning 'after, behind'. The following examples illustrate postcedents:
Postcedents are rare compared to antecedents, and in practice, the distinction between antecedents and postcedents is often ignored, the term "antecedent" being used to denote both. This practice is a source of confusion and some have therefore denounced the term "antecedent" outright because of this confusion.
Implied antecedents.
Some proforms lack a linguistic antecedent (or postcedent). In such cases, the antecedent is implied in the given discourse environment or from general knowledge of the world. For instance, the first person pronouns "I", "me", "we", and "us" and second person pronoun "you" are proforms that usually lack a linguistic antecedent. However, their antecedents are present in the discourse context as the speaker and the listener. Pleonastic proforms also lack a linguistic antecedent, e.g. "It is raining", where the pronoun "it" is semantically empty and cannot be viewed as referring to anything specific in the discourse world. Definite proforms such as "they" and "you" also have an indefinite use, which means they denote some person or people in general, e.g. "They will get you for that", and therefore cannot be construed as taking a linguistic antecedent.