Past tense of 'ape': to imitate or copy someone's behavior, speech, or mannerisms, often in a mocking way.
From Old English 'apa' (ape, the animal), which came from Latin and ultimately a West African language. The verb meaning 'to imitate' developed because apes were observed mimicking human gestures, giving rise to the figurative sense.
The word 'ape' for imitation literally comes from watching apes imitate humans—so when you 'ape' someone, you're doing what the animal does naturally, which is why it implies both imitation and often mockery.
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