From Middle English *ongang, *ongong, from Old English ongang (“entrance, incursion, irruption, assault, attack; worship”), equivalent to on- + gang.
ongang (plural ongangs)
- (UK dialectal) A start-up; beginning; commencement (of activity, work, machinery, etc.); a setting in motion.
- (UK dialectal) Rowdy or unrestrained behaviour; antics.