countersuit
noun
coun·ter·suit
| \ ˈkau̇n-tər-ˌsüt
\
\
variants:
or less commonly counter-suit
plural countersuits
also counter-suits
Definition of countersuit
: an opposing lawsuit
especially
: a claim asserted by an opposing party in a lawsuit (such as a defendant) against the party bringing the original lawsuit (such as a plaintiff) : counterclaim
decided to file a countersuit against her accuser The current appeal results from a patent infringement suit and countersuit between Apple Inc. ("Apple") and Samsung Electronics Co … — Apple, Inc. v. Samsung Electronics Co., Ltd.