Mysia = "land of beach trees"
1) a province of Asia Minor on the shore of the Aegean Sea, between Lydia and Popontis; it included the cities of Pergamos, Troas, and Assos
Part of Speech: noun proper locative
Of uncertain origin; Mysia, a region of Asia Minor: - Mysia.
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 Μυσία; click on the second column to search for that grammatical form of the root Μυσία; click on the third column to search for that word and grammatical form; click on the total to search for the root Μυσία.