English definition of “act”
DO [C] › something that someone does: an act of terrorism/kindness
LAW [C] › a law made by a government: an act of Congress/Parliament
THEATRE [C] › one of the parts a play is divided into: Her character doesn't appear until Act 2.
PERFORMERS [C] › one or several performers who perform for a short while in a show: a comedy double act
FALSE BEHAVIOUR [no plural] › behaviour which hides your real feelings or intentions: Was she really upset or was that just an act?
in the act (of doing sth) › doing something wrong: I caught him in the act of opening one of my letters.