mid-14c., "morally weak," from Old French fraile, frele "weak, frail, sickly, infirm" (12c., Modern French frêle), from Latin fragilis "easily broken" (from PIE root *bhreg- "to break"). It is the Frenchified form of fragile. Sense of "easily destroyed, liable to break" in English is from late 14c. The U.S. slang noun meaning "a woman" is attested from 1908; perhaps with awareness of Shakespeare's "Frailty, thy name is woman."