What does "bygones" mean?

Things that happened in the past.

Bygones

Common synonyms include: archival material, archival records, former times, historical artifacts, historical events, historical matters.

/ˈbaɪˌɡɑnz/ noun

noun ·Rare ·Advanced level

Noun

1
Things that happened in the past. plural, plural-normally
"[…] if you spare me, bygones are bygones, and when you fellows are in court for piracy, I'll save you all I can."

"Isn't it about time you guys buried the hatchet and let bygones be bygones?"

Plural of bygone (noun).