The word hamstrings is a noun. It is the plural form of hamstring.
Hamstrings
Your hamstrings help to extend your knees and your hips.
The part of speech for this particular word is a noun.
part of speech
The part of speech for "answer" is a noun.
what part of speech is beneath
adverb
The part of speech for "explicit" is an adjective.
The part of speech for "lecturer" is a noun.
The part of speech for "rapid" is an adjective.
The part of speech for "breezy" is an adjective.
The part of speech for "buried" is a verb.