The terms "incelibate" or "incel" are abbreviations of "involuntary celibate", coined in 1739 by Antoine Banier. It is one of many other terms that describe involuntarily celibate people. See the articles synonyms and synonyms of inceldom for a summary. But why has the term "incel" caught on? Why haven't any of the other terms with a similar meaning been as catchy or as popularized? This can be explained by two generalized factors; (a) phonetics and (b) accuracy. Ton den Boon was the first lexicographer to define the term "incel", defining it as a gender-neutral noun, meaning someone who lives involuntarily celibate.
The equivocal nature of its etymological derivatives means that "incel" is a catch-all term that covers everyone who seems to be unable to get a romantic partner. This is unlike "love-shy" which is primarily focused on mentalcels, or "TFL" which has a specified focus on peculiar causes, and uses the word "forced" thereby hinting at an external overbearing entity.
Some critics criticize the term "involuntary celibacy" without having a full grasp of of the scope of the terms "involuntary" or "celibacy". "Involuntary" is simply another word for unintentional; celibacy has a broader scope too as explained in the "polyseme" section.
The term "incelibate" has only four syllables and is thus easy to pronounce. The term "incel" has even less syllables; two, and is thus even easier to pronounce. The former has the advantage of being instantly recognizable since "celibate" is contemporary and in widespread usage, while for the latter there are no other words in the English language with close very permutations, sounds, or semantic equivalence.
The only reason that incels or incelibates use an abbreviated form of the longer term is that, "incel", has only two syllables, thus is easier to say. "Incelibate" has four syllables, again easy to say. In contrast, the term "involuntarily celibate person" has 11 syllables, which is much harder to say. Therefore, the term "incel" is to "involuntary celibate" the same thing as what "lb" is to "pound". "Incelibate" is to "involuntarily celibate" the same as what "USA" is to the "United States of America". Just because a longer term is abbreviated doesn't mean that the definition has changed. So in a nutshell, "incel" is simply an abbreviation of the term "involuntarily celibate".
The terms are simplified with its usage of simple grammar that befits Ogden's basic English. As such, it is easily malleable for linguistic morphology, which has been fully utilized in the incelosphere with the additional coinages of multiple derivatives through additions of affixes, such as in "inceldom", or prefixes, as in "mentalcel" etc. Both abbreviations are also catchy. The longer way of saying "incel" is "involuntarily celibate person", however this lengthened term is rarely used because it has 11 syllables.
Although there are many synonyms of incel, the reason incel has caught on in public discourse over the other terms in because it rolls off the tongue so easily. Another factor is probably the "in" aspect of the term incel. Many incels feel that their inceldom is a situation or circumstance that they are in. As such, sometimes the adoption of a word is largely because of the way it sounds. For example, if I called you a schmuck, and you had never heard the word schmuck before, you might gather that its an insult even if you didn't know the meaning of the word. That's because the word schmuck just sounds a certain way that indicates that it is not a compliment.
The other reason why the term "incel" has caught on is the accuracy of its unabbreviated form "involuntary celibacy". The nonsexuality article explains how people who don't understand inceldom sometimes conflate it with other forms of sexual inactivity even though incelibacy is very different. The term "involunarily celibate" is criticized as a misnomer on some platforms owing to the fact that "celibacy" is sometimes claimed to be by definition voluntary. This logic is faulty on three pillars; firstly one of the perks of the English language is that adjectives permit altering the meaning of the following noun. Secondly, the English language is filled with terms that on the surface seem like a misnomer but are in practise standard usage. For example Guinea pigs originate in the Andes, not in Guinea. Thirdly, although it is true that celibacy is overwhelmingly used in volitional contexts, it has also often been used in nonvolitional contexts.
One of the upsides in the usage of "involuntary celibacy" is that it has a broad enough scope that it includes those who seek only sex, those who seek only romance as well as those who seek a combination of the two. This means that "involuntary celibacy" is less exclusive than a term such as "involuntary sexual abstinence" which would allude only to sex. Furthermore, incelibates, as well as academics who have studied inceldom, often believe that there are societal factors behind inceldom. As such, it becomes succinct to coin a protologism that has societal or cultural undertones. Nobody can argue that the term "celibacy" lacks societal or cultural undertones due to its long tradition in Catholicism.
Finally, the word "involuntary" in "involuntary celibacy" makes it somewhat of an umbrella term. The adjective "involuntary" is intentionally broad enough that it includes individuals from a broad spectrum of emotional or subjective experiences, including those who are angry about their situation, as well as those who are content with their situation. Although the terms "nonvolitional" and "unintentional" have identical meanings to "involuntary", the former two have the disadvantage of having the prefixes "non-" and "un-" that makes them intractably associated with a determinative rather than the intention of the coinage as a noun.
Furthermore, not a single English dictionary has the words "responsibility" or "imposition" in the entries for "involuntary" or its synonym "unintentional". As such, it makes no sense to imply that the usage of the term "involuntary" implies blaming anyone for inceldom since the word involuntary is unloquacious on the matter of morality.
The most common criticism of the term "incel" is the suggestion that its unabbreviated form "involuntary celibacy" is a misnomer, misconstruction or oxymoron. However, all these criticisms can be countered by the existence of polysemes which are well-established in the English language. These critics argue that it is a misnomer because "celibacy" is by definition voluntary. For example a veggie burger at first glance seems to be contradictory since burgers by definition have meat. But does that mean we should go to fast food joints and deride them for bludgeoning the English language if they sell veggie burgers? The counter-argument to this criticism is that words can have multiple senses. Although it is true that "celibacy" usually refers to a voluntary (or volitional) act, lexical semantic fields such as homonyms and polysemes prove that a single word can have multiple meanings. The former refers to words with the same spelling but unrelated meanings, the latter to same spellings with similar meanings. The term "incel" is derived from the non-volitional sense of "celibacy". As such, the term incel is a hyponym of a polyseme of the most common usage of the term celibacy.
Another counterargument to the misnomer proponents is pointing to protologisms. The English language is ever evolving, like other languages, because of gaps in the langauge. As such, English is not a perfect linguistic system with a word for every conceivable concept. In such a "gap" scenario, sometimes the most logical course is to utilize the nearest synonym to the concept you're trying to convey. This evolution of language is how "incel" went from complete obscurity, to suddenly being a ubiquitous word.