What term is used for a word that can replace a noun or noun phrase?

The term that refers to a word that can replace a noun or noun phrase is "pronoun." Pronouns serve the function of representing nouns in order to avoid repetition and to streamline sentences. For example, in the sentence "Maria loves her dog because Maria takes it for walks," the pronoun "it" replaces the noun phrase "her dog."

The other options, while they play important roles in sentences, do not fulfill this specific function. An adjective describes or modifies a noun but does not replace it. An adverb modifies verbs, adjectives, or other adverbs and does not have the capacity to take the place of a noun. A conjunction connects words, phrases, or clauses but again does not serve as a substitute for nouns. Thus, when seeking a word that may replace a noun or noun phrase, the correct designation is indeed a pronoun.