A clumsy or foolish person, or someone who moves awkwardly.
From Middle English 'arse' (buttocks) + 'foot', a compound insult suggesting someone is as awkward as if they were walking on their rear end instead of their feet. This is a folk-etymological or derisive term from medieval English.
This wonderfully crude medieval insult reveals how people in the 1400s created vivid, physical insults by combining body parts—the 'arse' component appears in many old slang terms because it was seen as an inherently ridiculous body part.
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