From WordNet (r) 3.0 (2006) [wn]:
dozen
adj 1: denoting a quantity consisting of 12 items or units [syn:
twelve, 12, xii, dozen]
n 1: the cardinal number that is the sum of eleven and one [syn:
twelve, 12, XII, dozen]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Dozen \Doz"en\ (d[u^]z"'n), n.; pl. Dozen (before another
noun), Dozens (d[u^]z"'nz). [OE. doseine, dosein, OF.
doseine, F. douzaine, fr. douze twelve, fr. L. duodecim; duo
two + decem ten. See Two, Ten, and cf. Duodecimal.]
1. A collection of twelve objects; a tale or set of twelve;
with or without of before the substantive which follows.
"Some six or seven dozen of Scots." "A dozen of shirts to
your back." "A dozen sons." "Half a dozen friends."
--Shak.
[1913 Webster]
2. An indefinite small number. --Milton.
[1913 Webster]
A baker's dozen, thirteen; -- called also a long dozen.
[1913 Webster]