Word Origin & History
suffix expressing ability, capacity, fitness, from Fr., from L. -ibilis, -abilis, forming adjectives from verbs, from PIE *-tro-, a suffix used to form nouns of instrument. In L., infinitives in -are took -abilis, others -ibilis; in Eng., -able is used for native words, -ible for words of obvious L.
origin. The Latin suffix is not etymologically connected with able
, but it long has been popularly associated with it, and this has contributed to its survival as a living suffix. It is related to the second syllable of rudder