chancellor (n.)
early 12c., from Old French chancelier (12c.), from Late Latin cancellarius "keeper of the barrier, secretary, usher of a law court," so called because he worked behind a lattice (Latin cancellus) at a basilica or law court (see chancel). In the Roman Empire, a sort of court usher; the post gradually gained importance in the Western kingdoms. A variant form, canceler, existed in Old English, from Old North French, but was replaced by this central French form.