1.
If you ~ when someone hits you, or hit them back, you hit them in return.
Some violent men beat up their sons, until the boys are strong enough to ~...
If somebody hit me, I’d hit him back.
PHRASAL VERB: V P, V n P
2.
If you ~ at someone who has criticized or harmed you, you criticize or harm them in return. (JOURNALISM)
The President has ~ at those who have criticised his economic reforms...
British Rail immediately ~ with their own cheap fares scheme.
= strike back
PHRASAL VERB: V P at n, V P