Foolish

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Middle English: from Old French fol ‘fool, foolish’, from Latin follis ‘bellows, windbag’, by extension ‘empty-headed person’.

wiktionary

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From Middle English folisch; equivalent to fool +‎ -ish.

etymonline

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foolish (adj.)

early 14c., from fool (n.1) + -ish. Older adjectives in Middle English were fool (c. 1200); folly (c. 1300). Old English words for this were dysig, stunt, dol. Related: Foolishly; foolishness.