1. act, v. ANALYSIS: from actum by dropping the termination um. DEFINITION: to do, to perform. The noun "act" is formed in the same way. DEFINITION: a thing done, a deed or performance.
2. ac'tion: act + ion = the act of doing: hence, a thing done.
3. act'ive: act + ive = having the quality of acting: hence, busy, constantly engaged in action.
4. act'or: act + or = one who acts: hence, (1) one who takes part in anything done; (2) a stage player.
5. a'gent: ag + ent = one who acts: hence, one who acts or transacts business for another.
6. ag'ile: ag + ile = apt to act: hence, nimble, brisk.
7. co'gent: from Latin cogens, cogentis, pres. part, of cog'ere (= co + agere, to impel), having the quality of impelling: hence, urgent, forcible.
8. enact': en + act = to put in act: hence, to decree.
9. transact': trans + act = to drive through: hence, to perform.