''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 Big ''O'' notation is a mathematical notation that describes the limiting behavior of a function when the argument tends towards a particular value or infinity. Big O is a member of a family of notations invented by Paul Bachmann, Edmund Land ...

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 "''Directorium''" is a Latin word denoting a guide. In the later Middle Ages it was specially applied to Catholic liturgical guides for praying the Divine Office and Holy Mass. Early history For example, in the early fifteenth century Clement Ma ...

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 The '' Star Wars: Knights of the Old Republic'' series consists of '' Star Wars: Knights of the Old Republic'' and '' Star Wars: Knights of the Old Republic II – The Sith Lords'', with the first game being released in 2003 and set 4,000 year ...

, 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 ''Cryptonomicon'' is a 1999 novel by American author Neal Stephenson, set in two different time periods. One group of characters are World War II-era Allied codebreakers and tactical-deception operatives affiliated with the Government Code an ...

'', 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 Order of Mass is an outline of a Mass celebration, describing how and in what order liturgical texts and rituals are employed to constitute a Mass. The expression Order of Mass is particularly tied to the Roman Rite where the sections under that ...

, the order (regulation) of the Eucharist in the Roman Rite of the Catholic Church

See also