"Chiefly Law . Especially of a document: having the function of citing or summoning someone; relating to or concerned with this action. Especially in letters citatory (also citatory letters). Now chiefly historical", Late Middle English. From post-classical Latin citatorius of or relating to a legal summons (from late 12th cent. in British sources; also in continental sources; compare earlier citatorium (noun) legal summons) from classical Latin citāt-, past participial stem of citāre + -ōrius.[citatory etymology, citatory origin, 英语词源]