* Adjective: This is the most common usage. It describes something given or offered free of charge.
* Example: "The hotel offered a complimentary breakfast."
* Noun: This usage refers to a complimentary remark or expression of praise.
* Example: "The customer gave the waiter a complimentary remark about the service."
* Verb: This usage means to express admiration or praise.
* Example: "The speaker complimented the audience on their participation."
It's important to consider the context to determine the correct part of speech.