B1
one of the parts a play is divided into
Dictionary examples:
Act 2 was so boring, even the actors started falling asleep. (0.0)
The audience was shocked when a real pizza was delivered in Act 2. (0.0)
The cat stole the show in Act 1 by chasing a real mouse onstage. (0.0)
Her character doesn't appear until Act 2. (21.5)