The species descriptor should be an adjective that differentiates a species from other members of a genus. The genus name and species descriptor are usually derived from Latin, although Latin derivation is not universal. Names sometimes come from Ancient Greek, or from local languages, or from the name of the person who first discovered the species. In fact, taxonomists come up with species names from a variety of sources, including in-jokes and puns. However, names are always treated grammatically as if they were Latin words. For this reason the binomial name of a species is sometimes called its "Latin name," although this terminology is frowned upon by biologists. The term scientific name, however, is considered acceptable.