A person, who desperately desires certain sexual lifestyle and
relationships, that they are unable to achieve.
In reality: one of many sexist terms
used by normie
psychopaths to bully and shame (out of a discussion) single (usually low 'sexual market value') usually males, even if they aren't looking for a
relationship or aren't having 'incel behavior'; especially when they're venting about any hardship or unfairness to themselves in general, critical about women in general or about whatever she's just said specifically.
"incel behavior" is a stereotype of an assertive reaction to having your
sexual fantasy not fulfilled (other's sexual treatment of you) - by trying to (sometimes publicly - to "play the crowd"): demean/humiliate, shame/slander, all of which is usually 'it's not me - it's you' logic, for example when: getting sexually denied (in a decent way), or someone isn't as actively interested in you as you want them to be, or isn't giving you the type of attention; To save own ego, to validate your schizo social fantasy - 'social perception' of you by others as a 'valid sex option'.
Usually happens when you want them to be a certain way for you - e.g. submissive or simping - and they aren't, but you're too much of a narcissist/control freak to let go and move on.