* Noun: When referring to the act of asking questions or seeking information.
* Example: "The police are conducting an inquiry into the missing person's case."
* Verb: When it means to ask questions or seek information.
* Example: "The lawyer inquired about the witness's alibi."
* Adjective: Less common, but can be used to describe something related to questioning or investigation.
* Example: "The inquiry committee was tasked with reviewing the company's policies."
So, the part of speech depends on the context. You need to look at how it is used in the sentence to determine which part of speech is being used.