Parthian shot
noun
1.
a sharp, telling remark, act, gesture, etc., made in departing.
Origin
1900-05;
so called from the ancient Parthian cavalry's habit of shooting arrows rearward at the enemy while in real or feigned flight
British Dictionary definitions for
Parthian shot
Parthian shot
noun
1.
another term for
parting shot
Word Origin
alluding to the custom of Parthian archers who shot their arrows backwards while retreating