Of or pertaining to one of several persons-popes and others-named Gregory; especially, pertaining to Pope Gregory I., the Great (a. d. 590–604), or to Pope Gregory XIII. (1572–85).n. One of a club or brotherhood somewhat similar to the Freemasons, which existed in England in the early part of the eighteenth century. See Gormogon.n. A kind of wig worn in the seventeenth century: so named, it is said, from the inventor, one Gregory, a barber in the Strand, London.n. In music, a melody written in one of the church modes; a piece of plainsong.