In mathematics, the term 'order' has many different meanings. Among these are: (1) the sequence in which a set of objects or numbers is placed; (2) the number of elements in a set; (3) the number of times a shape can be fitted back onto its own outline during a complete turn (order of symmetry); (4) the highest order power in a one-variable polynomial (order of a polynomial, also known as its degree); (5) the type of curve described by such a polynomial (order of a curve).


In biology, order is a taxonomic rank below class and above family. Order names are printed in Roman (ordinary) letters, and begin with a capital letter. Among animals, the names of most orders end in -a, such as Anura (frogs and toads) and Chiroptera (bats), although bird orders end in -iformes, such as Columbiformes (pigeons) and Stringiformes (owls). In plants, order names generally end in -ales, such as Rosales (roses).