* Adjective: This is the most common usage. It describes something that is not definite or specific, such as "an indefinite amount of time."
* Noun: "Indefinite" can be used as a noun to refer to the concept of being indefinite, such as "The future is full of indefinite possibilities."
* Adverb: While less common, "indefinitely" can be an adverb meaning "for an unlimited or unspecified time," such as "The event will continue indefinitely."
The specific part of speech will depend on the context in which the word is used.