Um no, it's quite literally not. If you rubbed your two braincells together and just did some quick research on google, you'd know you're unequivocally wrong.
All cuckoldry is swinging, but not all swinging is cuckoldry. Cuckolds are into the submissive and/or humiliating aspects of sharing, and it isn't a mutual swinging experience, rather a one sided (consensual) experience. If both partners are getting action, then neither is a cuck, they're just a couple who likes to have fun and be adventurous and are your more broad swingers, instead of a more narrowed fetish within swinging, like a cuckold.
If you want to keep being ignorant, and just throw buzzwords and terms around that you have no idea the actual definition of, until those terms eventually lose all meaning (which is already happening), then that's your prerogative. But don't come in here presenting something as fact that you have absolutely no idea what you're talking about, it just makes you look stupid.