Derivational suffix in adjectives from Latin or Old French: convertible, digestible, forcible, impossible, terrible, etc.; also in ME derivatives: credibli, impossiblenesse, pesibli, unpossible, etc. It is rare in ME formations but probably occurs in permiscible 'capable of being mixed' (*Norton OAlch. vr.), although this may be merely a variant of permissible. Some words formerly thought to be of ME origin are now known to have ML etyma: extendible, reducible, revertible, etc.