the word 'weighty' is a native english formation, built upon the noun 'weight'. the noun 'weight' itself has a complex history, originating from the old english 'wiht', which broadly meant 'a thing' or 'a being'. this sense of a concrete entity evolved, under the influence of old norse and other germanic languages, to specifically denote the 'heaviness' of an object, a measurable physical property. the addition of the productive adjectival suffix '-y', descended from old english '-ig', transforms this noun into an adjective, literally meaning 'full of weight' or 'characterized by heaviness'. over time, this physical sense naturally extended metaphorically to describe matters of serious import or substantial consequence, mirroring the figurative use of 'heavy' to mean 'grave' or 'important'.

Structure: weight (heaviness) + y (adjective-forming suffix) - weight: from old english 'wiht' (a thing, a being, a creature), later influenced by old norse 'vætt' and middle low german 'wicht', evolving to mean 'heaviness'. in this compound, it provides the core meaning of 'heaviness'. - y: a native english suffix from old english '-ig', used to form adjectives meaning 'characterized by' or 'full of'.