Frivolous

google

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late Middle English: from Latin frivolus ‘silly, trifling’ + -ous.

wiktionary

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From Latin frīvolus(“silly, empty, trifling, frivolous, worthless”), with the ending modified to match -ous.

etymonline

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frivolous (adj.)

mid-15c., from Latin frivolus "silly, empty, trifling, worthless," diminutive of *frivos "broken, crumbled," from friare "break, rub away, crumble" (see friable). In law (by 1736), "so clearly insufficient as to need no argument to show its weakness." Related: Frivolously; frivolousness.