COS kôs. The name appears in KJV as COOS. An island of the Sporades group which formed a navigational point for Paul’s ship on the voyage from Ephesus to Rhodes (Acts 21:1). The island was prob. colonized from Epidaurus, and suffered heavily at the hands of both sides in the great war between Athens and Sparta which closed near the end of the 5th cent. b.c. Under Athenian control in the early 4th cent., the island revolted in 354 b.c. only to fall under the domination of Macedon. Its greatest fame flows first from the fact that it was the home of Hippocrates, the founder, in the 5th cent. b.c., of all medical science, and secondly from the fact that, in Hel. times, it was a center of lit. Under the protection of the Ptolemies of Egypt. It was the home of the writers Philetas and Theocritus. In the 2nd cent. b.c., Cos was loyal to the Romans, and became a free state within the province of Asia.