What does "baker" mean?

Baker: A portable oven in which baking is done. [U.S.] A baker's dozen, thirteen. -- Baker foot, a distorted foot. [Obs.] Jer. Taylor. -- Baker's itch, a rash on the back of the hand, caused by the irritating properties of yeast. -- Baker's salt, the subcarbonate of ammonia, sometimes used instead of soda, in making bread.