Webster's Revised Unabridged Dictionary · 1913

Overact

Overact , transitive verb

1.
To act or perform to excess; to exaggerate in acting; as, he overacted his part.
2.
To act upon, or influence, unduly. [Obsolete]
The hope of inheritance overacts them. — Milton

Overact , intransitive verb

To act more than is necessary; to go to excess in action. — B. Jonson