counter-

1.
a combining form of counter3 , used with the meanings “against,” “contrary,” “opposite,” “in opposition or response to” (countermand); “complementary,” “in reciprocation,” “corresponding,” “parallel” (counterfoil; counterbalance); “substitute,” “duplicate” (counterfeit).
Origin
Middle English countre-; see counter3
British Dictionary definitions for counter-

counter-

prefix
1.
against; opposite; contrary: counterattack
2.
complementary; corresponding: counterfoil
3.
duplicate or substitute: counterfeit
Word Origin
via Norman French from Latin contrā against, opposite; see contra-
Word Origin and History for counter-

word-forming element meaning "against; in return; corresponding," from Anglo-French countre-, French contre-, from Latin contra "opposite, contrary to, against, in return," also used as a prefix (see contra-).

counter- in Medicine

counter- pref.

  1. Contrary; opposite; opposing: countertransport.

  2. Corresponding; complementary: counterincision.