the word 'stealthy' originates from the old english noun stælþ, which meant 'theft' and was derived from the verb stelan, 'to steal'. the core concept of moving or acting secretly to take something illicitly evolved into the broader modern sense of any furtive or clandestine action. the addition of the adjectival suffix '-y', from old english -ig, transformed the noun into an adjective describing something characterized by stealth. thus, the literal progression is from 'the act of stealing' to 'having the qualities of secretive movement or action'.

Structure: stealth (noun) + y (adjective-forming suffix) stealth (from old english stælþ, meaning 'theft', from stelan 'to steal') + y (old english -ig, a suffix forming adjectives meaning 'characterized by' or 'full of').