The word 'uncountable' is a relatively modern English formation, built from native and borrowed elements. Its core, 'count,' entered English from Anglo-French cunter, which itself descended from Latin computare, meaning "to sum up, calculate." The negative prefix 'un-,' of Old English origin, is one of the most productive in the language for creating opposites. The suffix '-able,' from Latin -abilis via French, attaches to verbs to form adjectives meaning "liable to" or "capable of." Therefore, the literal morphemic construction "not capable of being counted" directly and logically yields the modern meanings, describing either an immense quantity or a grammatical category of nouns that resist enumeration.

Structure: un (not) + count (enumerate) + able (capable of) - un: A prefix of Germanic origin (Old English), meaning "not," used to form negatives. - count: A verb of Latin origin (computare), via Anglo-French, meaning to enumerate or calculate. - able: A suffix of Latin origin (-abilis), via Anglo-French, meaning "capable of, fit for, or worthy of."