Is the word all a noun adjective or a verb?

The Word 'all' is an adjective (describes a noun), an adverb (modifies a verb, an adjective, or another adverb), and an indefinite pronoun (take the place of a noun for an unknown or an unnamed quantity). Examples:

adjective: All participants have volunteered their time.

adverb: She ran all over the house looking for it.

indefinite pronoun: All I have is two dollars.