I. əˈpōnənt noun
( -s )
Etymology: Latin opponent-, opponens, present participle of opponere to place against, oppose, from ob- + ponere put, place — more at position
1.
a. : one that opposes a tenet or thesis in a disputation, argument, or other verbal controversy
b. archaic : one that opens an academic disputation by attacking a thesis or proposition — distinguished from respondent, defendant
2. : one that opposes : adversary , foe
3. : a muscle that opposes or serves to counteract and limit the action of another : antagonist
II. adjective
Etymology: Latin opponent-, opponens
1. : opposing , adverse , antagonistic
2. : situated in front : opposite