Dozen: The number twelve of things of a like kind; as a dozen of eggs.
Dozen comes from Old French dozaine, meaning: a dozen. Dozaine derives from and earlier word doze, meaning: twelve. Doze is from Latin word for twelve, duodecim. Duodecim is a combination of duo: two, and decem: ten.
Oh, and remember:
“By working faithfully eight hours a day, you may eventually get to be boss and work twelve.” – Robert Frost