• The group of (usually at least four) defensive backs in American football and Canadian football
• An obsolete name for the Mesozoic in geosciences
• The secondary winding, or the electrical or electronic circuit connected to the secondary winding in a transformer
• Secondary color
• Secondary consumers in ecology Trophic dynamics 
• Secondary dominant in music
• Secondary education
  • Secondary school - The type of school at the secondary level of education
• Secondary market, an aftermarket where financial assets are traded
• Secondary market offering
• Secondary mirror, second mirror element/focusing surface in a reflecting telescope
• Secondary neoplasm
• Secondaries, the second-largest group of remiges (wing feathers), which attach to the inner lower arm
• Private equity secondary, investment in an existing private equity fund or other alternative asset

• Le Secondaire était le nom d'une ère géologique (plus usité).
• Le secondaire, ou  enseignement secondaire, école secondaire, dans le système scolaire.
• Le secteur secondaire est un des secteurs d'activité économique.

• Educación secundaria.
• Color secundario.
• Efecto secundario.
• Caracteres sexuales secundarios.
• En una ficción, a un personaje secundario

Secundario,ria:

•Que viene en el segundo lugar en una serie.

•Derivado, accesorio.

•Aplicáse a la era caracterizada por la abundancia de moluscos, la existencia de gran variedad de reptiles y la aparición de aves y mamíferos.