Involuntary celibacy is the absence of intimate relationships or sexual intercourse for reasons other than voluntary celibacy or sexual abstinence. It describes those who, despite wanting sexual intimacy and potential romance and making repeated efforts towards such an end, cannot cause any such end(s) to occur with any significant degree of regularity — or even at all.

It is distinguished from other various celibacy types by two major overall characteristics: First, it is a pattern-like, semi-perpetual condition that cannot seem to improve despite concerted effort of the incel individual towards improving personal sex appeal and social skills to try to attract sexual partners. Second, involuntarily celibate individuals are at a complete or near-complete lack for intimate physical connection for very long spans of time — years and even sometimes decades, not merely weeks or months — and are also at a complete or near-complete lack of opportunities for sexual advancement in the first place, thereby making betterment of their own sexuality through accumulation of "sexual experience" impossible.

Many types of celibacy, including voluntary or semi-voluntary celibacy, exist throughout the spectrum of human sexuality; such instances of lack for sex are very common in the human experience. Involuntary celibacy is seen, chiefly by those who are affected by it, as a separate psychosocial issue to be taken seriously in its own right both because of the sheer extended lengths of time involved in incel "dry spells", and because such extended lack can have actual discernible negative consequences on a person's sexual development. However, despite corollaries such sleep-pattern clinics that study insomnia, sex research clinics do not seem to have much interest in studying incel.

Internet support groups exist, but because the causes of involuntary celibacy are so diverse and difficult to identify, there are no universally accepted behavioral or circumstantial alterations for overcoming the condition.