Vague (adj.) "uncertain as to specifics," 1540s, from Middle French vague "empty, vacant; wild, uncultivated; wandering" (13c.), from Latin vagus "strolling, wandering, rambling," figuratively "vacillating, uncertain," of unknown origin. Related: Vagueness.
Source : Online Etymology Dictionary
Note: The Online Etymology Dictionary maintains a free-access list of the origins of thousands of English words, a significant proportion of which are unknown
Also see: Sorites paradoxplugin-autotooltip__plain plugin-autotooltip_bigSorites paradox
The Sorites paradox is a philosophical problem dating from the time of Ancient Greece.
It relates to the problem of defining groups - specifically large groups. It has implications for the definitions of 'vagueness' 'fuzziness' 'blurriness' etc etc. Which in turn have implications for mathematics, modern computing systems (search algorithms, quantum computers, etc etc )