antagonize (v.)

1630s, "to compete with" (obsolete); 1742, "act in opposition to, struggle against continuously," from Greek antagonizesthai "to struggle against, oppose, be a rival," from anti "against" (see anti-) + agonizesthai "to contend for a prize," from agon "a struggle, a contest" (see agony). Meaning "make antagonistic" is by 1882. Related: Antagonized; antagonizing; antagonization.