bygones /ˈbaɪˌɡɑnz/noun 1forms 1phrases 1 noun[usually plural]1 •Things that happened in the past.[…] if you spare me, bygones are bygones, and when you fellows are in court for piracy, I'll save you all I can. — 1881 formsbygone Phrases with bygones let bygones be bygonesTo disregard or ignore a past difficulty in a relationship or an offence (when dealing with another individual).