Coos = "a public prison"
1) a small island of the Aegean Sea, over against the cities of Cnidus and Halicarnassus, celebrated for its fertility and especially for its abundance of wine and corn
Part of Speech: noun proper locative
Of uncertain origin; Cos, an island in the Mediterranean: - Cos.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root Κώς; click on the second column to search for that grammatical form of the root Κώς; click on the third column to search for that word and grammatical form; click on the total to search for the root Κώς.