In an arrogant or excessively proud manner; showing excessive confidence in one's abilities.
From conceited (past participle of conceit, from Old French conceite meaning 'idea' or 'conceit,' from Latin conceptus) + -ly. Over time, conceit shifted from 'a clever thought' to 'excessive pride.'
The shift in meaning from 'clever idea' to 'arrogant person' happened because conceited people often overestimate their cleverness—the word's meaning changed based on what it described!
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