- to act (a theatrical role) with insufficient emphasis or too great restraint
- underplay (sense )
verbun·der·act·ed, un·der·act·ing, un·der·acts
To perform (a theatrical role) weakly, with insufficient expressiveness, or with intentionally understated expressiveness.
To perform in an understated or unemotional way.
(third-person singular simple present underacts, present participle underacting, simple past and past participle underacted)
From under- +"Ž act.