What part of speech is endless?

"Endless" can be either an adjective or an adverb, depending on its use in a sentence.

* Adjective: Describing a noun.

* Example: "The ocean is an endless expanse." (Describing the noun "expanse")

* Adverb: Modifying a verb, adjective, or another adverb.

* Example: "The lecture went on endlessly." (Modifying the verb "went on")