gregorian

from The Century Dictionary.

• 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).
• noun 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.
• noun 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.
• noun In music, a melody written in one of the church modes; a piece of plainsong.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Pertaining to, or originated by, some person named Gregory, especially one of the popes of that name.
• adjective the calendar as reformed by Pope Gregory XIII. in 1582, including the method of adjusting the leap years so as to harmonize the civil year with the solar, and also the regulation of the time of Easter and the movable feasts by means of epochs. See Gregorian year (below).
• adjective (Mus.) plain song, or canto fermo, a kind of unisonous music, according to the eight celebrated church modes, as arranged and prescribed by Pope Gregory I. (called “the Great”) in the 6th century.
• adjective the musical scales ordained by Pope Gregory the Great, and named after the ancient Greek scales, as Dorian, Lydian, etc.
• adjective (Opt.) a form of reflecting telescope, named from Prof. James Gregory, of Edinburgh, who perfected it in 1663. A small concave mirror in the axis of this telescope, having its focus coincident with that of the large reflector, transmits the light received from the latter back through a hole in its center to the eyepiece placed behind it.
• adjective the year as now reckoned according to the Gregorian calendar. Thus, every year, of the current reckoning, which is divisible by 4, except those divisible by 100 and not by 400, has 366 days; all other years have 365 days. See Bissextile, and Note under Style, n., 7.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective of or relating to Pope Gregory I or to the plainsong chants of the Roman Catholic Church
• adjective of or relating to Pope Gregory XIII or the calendar he introduced in 1582