Emily Dickinson Lexicon

ACT, v.i. [Gr. αγω, L. ago, to urge, drive, lead, bring, do, perform; or in general, to move, to exert force; Cantabrian, eg, force; W. egni; Ir. eigean, force; Ir. aige, to act or carry on; eachdam, to do or act; actaim, to ordain; eacht, acht, deed, act, condition; Fr. agir; It. agire, to do or act.]

1. To exert power; as, the stomach acts upon food; the will acts upon the body in producing motion.
2. To be in action or motion; to move. He hangs between in doubt to act or rest. – Pope.
3. To behave, demean, or conduct, as in morals, private duties, or public offices; as, we know not why a minister has acted in this manner. But in this sense, it is most frequent in popular language; as, how the man acts or has acted. To act up to, is to equal in action; to fulfill, or perform a correspondent action; as, he has acted up to his engagement or his advantages.