Secondary may refer to:

Science and nature

Secondary emission In particle physics, secondary emission is a phenomenon where primary incident particles of sufficient energy, when hitting a surface or passing through some material, induce the emission of secondary particles. The term often refers to the emi ...

, of particles ** Secondary electrons, electrons generated as ionization products * The secondary winding, or the electrical or electronic circuit connected to the secondary winding in a

transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...

Secondary (chemistry) Secondary is a term used in organic chemistry to classify various types of compounds (e. g. alcohols, alkyl halides, amines) or reactive intermediates (e. g. alkyl radicals, carbocations). An atom is considered secondary if it has two 'R' Groups ...

, a term used in organic chemistry to classify various types of compounds *

Secondary color A secondary color is a color made by mixing of two primary colors in a given color space. Additive secondaries Light (RGB) For the human eye, good primary colors of light are red, green, and blue. Combining lights of these colors produces ...

, color made from mixing primary colors *

Secondary mirror A secondary mirror (or secondary) is the second deflecting or focusing mirror element in a reflecting telescope. Light gathered by the primary mirror is directed towards a focal point typically past the location of the secondary. Secondary mirro ...

, second mirror element/focusing surface in a reflecting telescope *

Secondary crater Secondary craters are impact craters formed by the ejecta that was thrown out of a larger crater. They sometimes form radial crater chains. In addition, secondary craters are often seen as clusters or rays surrounding primary craters. The study of ...

s, often called "secondaries" * Secondary consumer, in ecology * An obsolete name for the

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

in geosciences * Secondary feathers, flight feathers attached to the ulna on the wings of birds

Society and culture

Secondary (football) In gridiron football, defensive backs (DBs), also called the secondary, are the players on the defensive side of the ball who play farthest back from the line of scrimmage. They are distinguished from the other two sets of defensive players, the ...

, a position in American football and Canadian football * Secondary dominant in music *

Secondary education Secondary education or post-primary education covers two phases on the International Standard Classification of Education scale. Level 2 or lower secondary education (less commonly junior secondary education) is considered the second and final pha ...

, education which typically takes place after six years of primary education **

Secondary school A secondary school describes an institution that provides secondary education and also usually includes the building where this takes place. Some secondary schools provide both '' secondary education, lower secondary education'' (ages 11 to 14) ...

, the type of school at the secondary level of education *

Secondary market The secondary market, also called the aftermarket and follow on public offering, is the financial market in which previously issued financial instruments such as stock, bonds, options, and futures are bought and sold. The initial sale of the s ...

, an aftermarket where financial assets are traded

Science and nature

Society and culture

See also