1580s, "to torture," from Middle French agoniser or directly from Medieval Latin agonizare, from Greek agonizesthai "contend in the struggle" (see agony). Intransitive sense of "suffer physical pain" is recorded from 1660s; that of "to worry intensely" is from 1853. Related: Agonized; agonizing.[agonize etymology, agonize origin, 英语词源]
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.