Definition of "cuck"

Not the Horn-Plague, but something worse, Had drove the frighted Cucks from thence.

1706, Edward Ward, Hudibras redivivus, I.10

We bounce from Bisset and Seymour’s increasingly happy shagging to Worsley, the willing cuck, watching on and, finally, the trial that Worsley brings against Bisset.

2015 August 17, Filipa Jodelka, The Guardian

Jeff and Allison secretly live the "hotwife/cuckold" lifestyle.

2015, Carter Saint, Coming Out As a Cuck

“He starts getting in my face. Thomas puts his hand on the dude’s chest to stop him. ‘Don’t touch me you cuck. Wanna go outside?’”

2016, Kumail Nanjiani, quoted in The Guardian, 12 November

From there cuck evolved into a catch-all way of abusing men who might be otherwise referred to as “betas”.

2017 August 3, Tim Squirrell, “The evolution of "cuck" shows that different far-right groups are learning the same language”, in New Statesman

You're[sic] site is SHITE. It gets hacked DAILY. You dumb cuck.

2020, "TDO" quoted by Vinny Troia in Hunting Cyber Criminals

It’s redolent of the way establishment conservatives lost the culture war in the first place, by bowing to the opposition, allowing others to play them for fools, and contenting themselves with the occasional scraps thrown to them by progressive elites. I said “cucked by Zuck” earlier, but in reality, they were cucked a long time ago and by their enemies in the Democratic Party and liberal media.

2016 May 18, Milo Yiannopoulos, Cucked by Zuck‎

Follow the law, and you can cucke mee, spare not.

1611, Thomas Middleton, Thomas Dekker, The Roaring Girle