PIE base ‘to be strong, be lively’. See also PIE base *bheudh-, root of buddha ‘an awakened being’.
Other derivatives include reveille, surveillance, watch, wait, witch (as ‘one who wakes the dead’), vegetable (from Latin vegēre ‘to be lively’), velocity, vigil, and vigilant.
[Pokorny *u̯eg̑- ‘fresh, strong’, pp. 1117–1118]