 These words are usually marked in dictionaries with the phrase "plural in form but singular in construction" (or similar wording).Others, such as "aesthetics", are less strongly or consistently felt as singular; for the latter type, the dictionary phrase "plural in form but singular or plural in construction" recognizes variable usage.Some words of foreign origin are much better known in their (foreign-morphology) plural form, and are often not even recognized by English speakers as having plural form; descriptively, in English morphology many of these simply are not in plural form, because English has naturalized the foreign plural as the English singular.