Green’s Dictionary of Slang

1. (US campus) excellent, worthy of admiration.

1992		Eble Campus Sl. Apr.
1996		Eble Sl. and Sociability 56: The following functionally synonymous slang terms from two school years, 1990–91 and 1991–92, all mean ‘excellent, worthy of approval’: [...] decent, def, diva.

2. (S.Afr. gay) sexually sophisticated.

2003

K. Cage Gayle.