Secondary may refer to:

• Secondary emission, 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
• Secondary (chemistry), a term used in organic chemistry to classify various types of compounds
• Secondary color, color made from mixing primary colors
• Secondary mirror, second mirror element/focusing surface in a reflecting telescope
• Secondary craters, often called "secondaries"
• Secondary consumer, in ecology
• An antiquated name for the Mesozoic in geosciences
• Secondary feathers, flight feathers attached to the ulna on the wings of birds

• Secondary (football), a position in American football and Canadian football
• Secondary dominant in music
• Secondary education, education which typically takes place after six years of primary education
  • Secondary school, the type of school at the secondary level of education
• Secondary market, an aftermarket where financial assets are traded

• All pages with titles beginning with Secondary
• All pages with titles containing Secondary
• Second (disambiguation)
• Binary (disambiguation)
• Primary (disambiguation)
• Tertiary (disambiguation)