Ordo (Latin "order, rank, class") may refer to: A musical phrase constructed from one or more statements of a rhythmic mode pattern and ending in a rest Big O notation in calculation of algorithm computational complexity Orda (organization), also ordo or horde, was a nomadic palace for the Mongol aristocrats and the Turkic rulers Order (biology), in the taxonomy of organisms Ordo Recitandi or directorium gives complete details of the celebration of the Eucharist and the Liturgy of the Hours, beginning with the first Sunday of Advent Religious order in monasticism The Inquisition from Warhammer 40,000 has three main ordines: Ordo Malleus, Ordo Hereticus and Ordo Xenos Ordo Templi Orientis, an organization dedicated to the religious philosophy of Thelema The scholarly economic/political science journal The ORDO Yearbook of Economic and Social Order Canderous Ordo, a fictional character in the Star Wars video games Star Wars: Knights of the Old Republic and Star Wars Knights of the Old Republic II: The Sith Lords A fictional encryption program from the book Cryptonomicon, by Neal Stephenson Novus ordo seclorum which appears on the reverse of the Great Seal of the United States Ordo Missae or Order of Mass, the order (regulation) of the Eucharist in the Roman Rite of the Catholic Church See also Urdu