fragile (adj.)
1510s, "liable to sin, morally weak;" c. 1600, "liable to break;" a back-formation from fragility, or else from Middle French fragile (Old French fragele, 14c.), from Latin fragilis "easily broken," from root of frangere "to break" (from PIE root *bhreg- "to break"). Transferred sense of "of frail constitution" (of persons) is from 1858.