Primary asemiosis, or (often euphemistically) cutie mark delay, is a disease condition of little ponies. Asemiosis is the absence of a natural cutie mark on a little pony, or an analogous marking on a zebra or shadhavar (glyph-mark or musical sigil.) Asemiosis is the normal condition of foals; it is not considered an abnormality until the 16th year, after which 99% of ponies have developed normal cutie marks. At twenty years of age, asemiotic ponies are very rare.
Some ponies with primary asemiosis really are just "cutie mark delayed" and get normal cutie marks after their 16th birthday, often for special talents that were inaccessible to them in foalhood. Others will go on to develop forms of dysemiosis, getting cutie marks that are amorphous or difficult to see due to lack of contrasting color. Some will simply never obtain a cutie mark in their natural life. Ponies with obscure cutie mark symbolism are sometimes misdiagnosed with dysemiosis. (One historical example is Eldritch Lore, whose cutie mark is an unusually shaped glyph.)
The great majority of ponies have their cutie marks by their teenage years, with the majority getting them while in elementary school. In society, asemiosis is sometimes stigmatized. Asemiotic ponies are sometimes popularly thought to be untalented or unmotivated. Others may speculate that their special talents are sexual, or even illicit, in nature. (In reality, less than 10% of primary asemiosis cases resolve with the discovery of a sexual or reproductive special talent after coitarche; cutie marks for illicit conduct are quite rare.)
No definitive therapy for primary asemiosis is known. Sufferers may wear concealing clothing, adopt false cutie marks with fur dye, or be open about their condition. Some attempt to take a positive view of the condition, considering themselves as generalists or renaissance mares. Other asemiotic ponies reject the idea that a cutie mark confers a special talent altogether, and lay claim to some particular skill - the condition, they argue, merely prevents a visible cutie mark, not the development of the special talent it would symbolize.