(written Cos in the R.V.), a small island, one of the Sporades in the Aegean Sea, in the north-west of Rhodes, off the coast of Caria. Paul on his return from his third missionary journey, passed the night here after sailing from Miletus (Acts 21:1). It is now called Stanchio.
Easton’s Bible Dictionary
Coos
Name meaningtop, summit
Easton’s Bible Dictionary (1897), public domain. Text via Theographic Bible Metadata, CC BY-SA 4.0.