Which term refers to a word used to replace a noun to avoid repetition?

The term that refers to a word used to replace a noun to avoid repetition is 'pronoun.' Pronouns serve the purpose of substituting for a noun or noun phrase. This allows for smoother and more varied sentence construction, enhancing readability and comprehension. For example, instead of repeating a noun like "the engineer," one might use "he" or "she" to refer back to that same person, thereby reducing redundancy in language.

The other options do not fulfill this function. A verb indicates an action or state of being, a noun identifies a person, place, thing, or idea, and an adjective describes or modifies a noun. None of these terms have the role of substituting for nouns in the way that pronouns do. Thus, the correct terminology to describe a word that avoids redundancy by standing in for a noun is indeed 'pronoun.'