They are TWO verbs: "might" plus the short form of the auxiliary verb "have" ('ve). When you analyse a text, you take them with the following verb, which must be another verb (You might've come - where "might" is one verb, and "'ve come" - another).
Might've
The part of speech for this particular word is a noun.
part of speech
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
I think it mightve been private lewis
The part of speech for "unfamiliar" is an adjective.
The part of speech of "came" is a verb.
The part of speech for "twirl" is a verb.
The part of speech for "explicit" is an adjective.
The part of speech for "indefinite" is an adjective.