This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

adj. Gone by; past: bygone days.

n. One, especially a grievance, that is past: Let bygones be bygones.

adj. Having been or happened in the far past.

n. A person or occurrence that took place in the past.

adj. Past; gone by.

n. Something gone by or past; a past event.

Past; gone by; hence, out of date; antiquated: as, “thy bygone fooleries,”

n. What is gone by and past: as, that is a bygone; let bygones be bygones; “let old bygones be,”

adj. well in the past; former

n. past events to be put aside

"The words used in bygone eras were not as sharp or short as they are now, and neither were the phrases."

past   

yesteryear    past    past times   

let bygones be bygones   

past    pass   

untold    long-ago    post-war    chivalric    olden    unclouded    eighteenth    Napoleonic    long-past    time-honored