fragile: [17] Fragile and frail [13] are doublets: that is to say, they have the same ultimate source but have evolved in different ways. In this case the source was Latin fragilis ‘breakable’, a derivative of the same base (*frag-) as produced frangere ‘break’ (whence English fractious). Fragile was acquired either directly from the Latin adjective or via French fragile, but frail passed through Old French frale or frele on its way to English. Other English words to come from *frag- include fragment [15] (from Latin fragmentum) and saxifrage, literally ‘rockbreaker’. => fraction, fracture, fragment, frail, saxifrage
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" (see fraction). Transferred sense of "of frail constitution" (of persons) is from 1858.
