a- (2)EnglishOxford New American Dictionarya-2/eɪ- / ▸ prefix to; toward: aside ashore. ▪ in the process of (an activity): a-hunting. ▪ in a specified state or manner: asleep aloud. ▪ on: afoot. ▪ in: nowadays. – ORIGIN Old English , unstressed form of on.