The word "unknowable" is a modern English formation built from native and borrowed elements. Its core, "know," originates from the Proto-Germanic knēaną, related to concepts of perception and recognition. The negative prefix "un-," also of ancient Germanic stock, is one of the most common negators in English. The adjectival suffix "-able" entered English via Old French from Latin, where it formed passive adjectives. Thus, the literal construction "not capable of being known" directly and logically yields the modern abstract meaning, describing something that lies beyond the limits of human knowledge or comprehension.

Structure: un (not) + know (to have knowledge) + able (capable of) - un: A prefix of Germanic origin (Old English), meaning "not," used to form negatives. - know: A verb from Old English cnāwan, of Germanic origin, meaning to perceive, understand, or be aware of. - able: A suffix from Latin -abilis, via Old French, meaning "capable of, fit for, or worthy of."