What is the term for a pronoun used as a direct object, indirect object, or object of the preposition?

The term for a pronoun used as a direct object, indirect object, or object of the preposition is indeed "object." In grammar, an object is typically a noun or pronoun that receives the action of a verb or that is governed by a preposition.

When a pronoun functions as a direct object, it receives the action performed by the subject of the sentence. For example, in the sentence "She called him," "him" is the direct object. As an indirect object, the pronoun indicates to whom or for whom the action is performed, as in "I gave her the book," where "her" is the indirect object. Additionally, when a pronoun serves as the object of a preposition, it follows the preposition, as seen in "They went with us," where "us" is the object of the preposition "with."

The other terms listed do not fit this definition; "subject" refers to who or what is doing the action in the sentence, "adverb" modifies verbs, adjectives, or other adverbs by providing additional context (like how, when, where, or to what extent), and "conjunction" is a word that connects clauses or sentences.