From WordNet (r) 3.0 (2006) [wn]:
deb
n 1: a young woman making her debut into society [syn:
debutante, deb]
From The Free On-line Dictionary of Computing (8 July 2008) [foldoc]:
deb
<filename extension, Debian> The filename extension for a
Debian binary package.
(2001-01-27)