1) a teacher
2) in the NT one who teaches concerning the things of God, and the duties of man
1a) one who is fitted to teach, or thinks himself so
1b) the teachers of the Jewish religion
1c) of those who by their great power as teachers draw crowds around them, i.e. John the Baptist, Jesus
1d) by preeminence used of Jesus by himself, as one who showed men the way of salvation
1e) of the apostles, and of Paul
1f) of those who in the religious assemblies of the Christians, undertook the work of teaching, with the special assistance of the Holy Spirit
1g) of false teachers among Christians
Part of Speech: noun masculine
Citing in TDNT: 2:148, 161
From G1321; an instructor (generally or specifically): - doctor, master, teacher.
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 διδάσκαλος; click on the second column to search for that grammatical form of the root διδάσκαλος; click on the third column to search for that word and grammatical form; click on the total to search for the root διδάσκαλος.