C17: from Greek antagōnizesthai, from anti- + agōnizesthai to strive, from agōn contest
Word Origin and History for antagonize
v.
1630s, "to compete with," from Greek antagonizesthai "to struggle against, oppose, be a rival" (see antagonist). Meaning "to struggle against continuously" is recorded from 1742. Related: Antagonized; antagonizing.