Areopagus = "martial peak"
1) a rocky height in the city of Athens, opposite the western end of the Acropolis toward the west.
Part of Speech: noun proper locative
From Ἄρης Arês (the name of the Greek deity of war) and a derivative of G4078; rock of Ares, a place in Athens: - Areopagus, Mars' Hill.
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 Ἄρειοσ-πάγος; click on the second column to search for that grammatical form of the root Ἄρειοσ-πάγος; click on the third column to search for that word and grammatical form; click on the total to search for the root Ἄρειοσ-πάγος.