The Bríatharogam (kennings) for the letter are: Its meaning is probably "[the act of] wounding".
It may be a verbal noun of gonid 'wounds, slays'.
in which case is related to Welsh gwanu 'to pierce, to stab', which comes from the root was *gʷhen- 'to pierce, to strike'.
Its original phonetic value in Primitive Irish was [ɡʷ], the voiced labiovelar.
In Old Irish, this phoneme merged with g (gort), and the medieval manuscript tradition assigns it Latin ng [ŋ], hence the unetymological spelling of the letter name with initial n-.