British spelling: to cause great suffering or distress, or to experience extreme mental or physical pain; to struggle intensely with a difficult decision or problem.
From French 'agoniser,' derived from Greek 'agon' (struggle). The verb entered Middle French from Late Latin 'agonizare,' which combined the Greek root with the Latin verb-forming suffix '-ize.'
The British spell it 'agonise' while Americans use 'agonize,' but both come from the ancient Greek word for contest—the idea is that you're wrestling with something painful, just like Greek athletes wrestling in competition.
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