See pronoun in Webster's New World College Dictionary
noun
Gram. any of a small class of relationship or signal words that assume the functions of nouns within clauses or phrases while referring to other locutions within the sentence or in other sentences: I, you, them, it, ours, who, which, myself, anybody, etc. are pronouns
See pronoun in American Heritage Dictionary 4
(prōˈnounˌ)
noun Abbr. pron. or pr.
The part of speech that substitutes for nouns or noun phrases and designates persons or things asked for, previously specified, or understood from the context.
Any of the words within this part of speech, such as he or whom.