Complain is classified as which part of speech?

The term "complain" is classified as a verb, which means it denotes an action or a state of being. In this context, it refers to the act of expressing dissatisfaction or annoyance about something. Verbs are crucial in sentences as they indicate what the subject is doing or what is happening.

When "complain" is used in sentences, it typically functions to convey a specific action, such as "He complained about the service." This further clarifies that the word represents a dynamic process rather than an object, quality, or circumstance, which would be indicated by a noun, adjective, or adverb.

In contrast, a noun would name a person, place, thing, or idea. An adjective describes or modifies a noun, and an adverb modifies a verb, an adjective, or another adverb. Since "complain" does not fulfill these roles, it firmly fits the classification of a verb.