playact vs underact

playact and underact both are verbs.

Word	Noun	Adjective	Verb	Adverb
playact	No	No	Yes	No
underact	No	No	Yes	No

As verbs, underact is a hyponym of playact; that is, underact is a word with a more specific, narrower meaning than playact:

Other hyponyms of playact include stooge, mime, pantomime, ham, ham it up, overact, overplay, underplay.

playact (verb)	underact (verb)
perform on a stage or theater	act (a role) with great restraint