Where does cuck come from?
Cuck is shortened from cuckold, a term that has been used to belittle the “husband of an unfaithful wife” since the 1200s. The word cuckold derives from a French word for the cuckoo bird. Just as the female cuckoo lays eggs in other birds’ nests, a cuckold’s wife, as it’s said, sleeps in another man’s bed.
In online message boards like 4chan over the 2010s, cuck slang developed racist and misogynistic undertones. Cuck porn, for instance, describes a genre of pornography featuring white husbands watching their wives have intercourse with black men. Among others, the implication is that such a husband is so weak he can’t do anything to stop her and so submissive he even observes the act. As linguist Mark Liberman explained on Language Log, cuck “was extended figuratively on 4chan to reference ‘relinquished manliness’ and more abstractly ‘selling out, abandoning principles.’”
While it’s unclear exactly who coined it and when, cuck eventually blended with conservative, yielding cuckservative. The term first appeared on Twitter in 2010, when it was used as a hashtag. This spread among white nationalists online, and they used cuckservative against conservative politicians who they felt were too sympathetic or accommodating to mainstream, inclusive, and pro-minority policies. Cuck rose to prominence during the 2016 US presidential election. In August 2015, The New York Times reported that the hashtag "#cuckservative" peaked during the GOP debates, when many social-media users slammed Republican candidates who had “veered too far to the left.”
By 2016, internet users were commonly clipping cuckservative back to cuck. Members of the American Dialect Society nominated the two words for their 2016 Word of the Year in a category called “WTF.”
Who uses cuck?
Conservative internet and social-media users most commonly use cuck as a slang insult for mainstream Republican politicians. Owing to its history and continued use among white nationalist groups, however, cuck still carries a racist and misogynistic subtext.
Cuck also maintains currency online to ridicule men perceived as unmanly. On social media, women users have appropriated the hashtag "#cuck" in various expressions of dominance over their male significant others. A notable example of this usage is against the boyfriend of Zoe Quinn (a video game developer and artist), who suffered extreme harassment during the 2014 Gamergate controversy. He was called beta cuck over his allegations that Quinn cheated on him.
Cuck can also be used against "sell outs" or people who seemingly abandon their principles. Comedian Louis C.K. is a notable example here, in that he was labeled as a cuck after he expressed resentment of progressive views in his standup.
@tedcruz Dude, this guy slagged off your wife and father. Why're you having dinner with him? Sad! #cuck #brownnosing #pathetic
@ItinerantCamel, March, 2017
As has been explained, 'cuck,' from cuckold, refers to a humiliated and powerless man whose wife cheats on him. It has been expanded in slang to mean any man who is seen as weak and unreasonably submissive to women.
/u/fuckyoudurangatang, Reddit, February, 2015
Cuckservative, cuck: The term 'cuckservative' originated in the alt-right. It's a portmanteau of 'conservative' and 'cuckold' used to describe Republicans who are perceived to be emasculated or 'selling out.' Frequently shortened to 'cuck,' the term has come under scrutiny for its racist implications.
Jessica Roy, “'Cuck,' 'Snowflake,' 'Masculinist': A Guide to the Language of the Alt-right’,” The Los Angeles Times, November, 2016