What kind of parts speech is fast?

"Fast" can be several parts of speech, depending on how it's used in a sentence:

* Adjective: Describing a noun (e.g., "The fast car zoomed by.")

* Adverb: Modifying a verb, adjective, or another adverb (e.g., "He ran fast." or "It was a fast-paced game.")

* Noun: Referring to the concept of speed (e.g., "He was known for his fast.")

Let me know if you'd like examples of how "fast" functions as each part of speech!