'cobwebby' originates from English, specifically the noun 'cobweb' + suffix '-y', where 'cob' (from Old English 'coppe') meant 'spider' and 'web' meant 'woven mesh or web'.

'cobweb' changed from the Old English word 'coppewebbe' (literally 'spider-web') and eventually became the modern English word 'cobweb'; the adjective 'cobwebby' was formed later by adding the adjectival suffix '-y'.

Initially related to spiders and their webs ('spider's web'), it came to mean specifically 'covered with cobwebs' and then extended figuratively to mean 'neglected' or 'old-fashioned'.