word-forming element expressing capability, capability, physical fitness, from French, from Latin -ibilis, -abilis, forming adjectives from verbs, from PIE *-tro-, a suffix accustomed develop nouns of tool. In Latin, infinitives in -are took -abilis, other individuals -ibilis; in English, -able is often used in combination with indigenous (as well as other non-Latin) terms, -ible with words of apparent Latin source (but there are exclusions). The Latin suffix isn't etymologically linked to in a position, however it long was popularly related to it, and also this has added to its success as an income suffix. It is related to the 2nd syllable of rudder and saddle.
An adjective suffix now typically in a passive sense; in a position to be; fit is; revealing capability or worthiness in a passive feeling; as, movable, capable of being relocated; amendable, able to be amended; blamable, fit is blamed; salable.
An adjective suffix today typically in a passive sense; capable of being; fit to be; expressing capability or worthiness in a passive good sense; because, movable, capable of being relocated; amendable, able to be amended; blamable, fit is blamed; salable.