COS, or COOS, in Ancient Geography, a noble island on the coast of Caria, in the Hither Asia, 15 miles to the west of Halicarnassus, 100 in compass, called Meropis; and hence Thucydides joins both names together, Cos Meropis; it had a cognominal town Cos, but originally called Astypalea, mentioned by Homer; with a port locked or walled round. (Soylax, Mela). The island was fruitful, and yielded a generous wine, (Strabo). It boasted of Hippocrates and Apelles; each at the head of his several profession. It was the country of Philetas, an excellent elegiac poet, who flourished in the time of Philip and Alexander: the preceptor of Ptolemy Philadelphus: so thin and light that he was obliged to wear lead to prevent the being blown away by a puff of wind (Ælian, Athenæus); much commended by Propertius. The vestes Coæ, made of silk, were famous for their fineness and colour, (Horace, Propertius, Tibullus). In the suburbs of Cos stood the temple of Æsculapius, a noble structure, and extremely rich.
Cos, the Whetstone, in Natural History, a genus of vitrescent stones, consisting of fragments of an indeterminate figure, sub-opaque, and granulated.
Of this genus there are several species, some consisting of rougher, and others of smoother, or even of altogether impalpable particles; and used not only for whetstones, but also for mill-stones, and other the like purposes.