• Primary (astronomy)
  Primary (astronomy)
  A primary is the main physical body of a gravitationally-bound, multi-object system. This body contributes most of the mass of that system and will generally be located near its center of mass....
  
  , the larger of two co-orbiting bodies
• Primary is used for the name of the primary mirror
  Primary mirror
  A primary mirror is the principal light-gathering surface of a reflecting telescope.-Description:The primary mirror of a reflecting telescope is a spherical or parabolic shaped disks of polished reflective metal , or in later telescopes, glass or other material coated with a reflective layer...
  
   in a telescope.
• Primary (band)
  Primary (band)
  Primary is a rock band based in Sydney, Australia from 1995 until the early 2000s. The band's nucleus consisted of Jamie Fonti , Sean Fonti and Connie Mitchell...
  
  , from Australia
• Primary circuit, electrical circuit in a Transformer
  Transformer
  A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...
  
   that receives current, as opposed to secondary circuit
• A primary election
  Primary election
  A primary election is an election in which party members or voters select candidates for a subsequent election. Primary elections are one means by which a political party nominates candidates for the next general election....
  
   by which a political party selects and nominates a candidate
• Power line
  Power Line
  Power Line is an American political blog, providing news and commentary from a conservative point-of-view. It was originally written by three lawyers who attended Dartmouth College together: John H. Hinderaker, Scott W. Johnson, and Paul Mirengoff...
  
   that is fed to or from a transformer
• Primary (film)
  Primary (film)
  Primary is a 1960 Direct Cinema documentary film about the 1960 Wisconsin Primary election between John F. Kennedy and Hubert Humphrey for the United States Democratic Party nomination for President of the United States....
  
  , 1960 documentary
• Primary (LDS Church), children's Sunday School organization
• "Primary" (song)
  Primary (song)
  "Primary" is the first single from The Cure's third studio album Faith, released in 1981 on Fiction Records. It was the first song by The Cure to be remixed as a separate extended mix for release on 12" single...
  
  , by The Cure
• Primary, the oldest period in the Geologic time scale
  Geologic time scale
  The geologic time scale provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth...
  
   (obsolete)
• "Primary", a song by Spoon from the album Telephono
  Telephono
  Telephono is the first album from Austin, Texas indie rock band Spoon. It was released on April 23, 1996 by Matador, then re-released in a two-disc package with the Soft Effects EP in 2006 by Merge Records....
  
  
• Primaries, remiges (wing feathers) in birds
• Primaries or primary beams, in E. E. Smith's science-fiction series Lensman
  Lensman
  The Lensman series is a serial science fiction space opera by Edward Elmer "Doc" Smith. It was a runner-up for the Hugo award for best All-Time Series ....
  
  

Mathematics

• Primary decomposition, a decomposition into primary ideals
• Primary group, or simply p-group
  P-group
  In mathematics, given a prime number p, a p-group is a periodic group in which each element has a power of p as its order: each element is of prime power order. That is, for each element g of the group, there exists a nonnegative integer n such that g to the power pn is equal to the identity element...
  
  , a group of prime power order
• Primary ideal
  Primary ideal
  In mathematics, specifically commutative algebra, a proper ideal Q of a commutative ring A is said to be primary if whenever xy is an element of Q then x or yn is also an element of Q, for some n...
  
  s, a concept in commutative algebra

See also

• Primary
  Swan (nuclear explosive)
  Swan was a U.S. test nuclear explosive.It was tested standalone as a test nuclear device on June 26, 1956 in shot Redwing Inca. It was tested again as the primary of a test thermonuclear device on July 2, 1956 in shot Redwing Mohawk. Both tests were successful in all respects. It subsequently...
  
  , the first stage in a thermonuclear explosive, may also be used alone in a lower-yield nuclear explosive
• Primary education
  Primary education
  A primary school is an institution in which children receive the first stage of compulsory education known as primary or elementary education. Primary school is the preferred term in the United Kingdom and many Commonwealth Nations, and in most publications of the United Nations Educational,...
  
  , the first stage of compulsory education
• Primary field
  Primary field
  In theoretical physics, a primary field is a field operator in quantum field theory - especially conformal field theory or a theory with supersymmetry - that is invariant under the positive frequency modes of the Virasoro algebra - or under one half of the supersymmetries and superconformal...
  
  , a type of field in conformal field theory
  Conformal field theory
  A conformal field theory is a quantum field theory that is invariant under conformal transformations...
  
  
• Primary Flight Training, in the U.S. Navy
• Primary FRCA
  Primary FRCA
  The Primary FRCA is more fully called the Primary Examination of the Diploma of Fellowship of the Royal College of Anaesthetists.Trainee anaesthetists in the United Kingdom are required to pass this examination before applying for Higher Specialist Training in Anaesthesia...
  
  , academic examination for anaesthetists in the U.K.
• Primary Music
  Primary Music
  Primary Music is an Israeli independent record label, specializing in World Music, New Age, Lounge and ambient. Primary Music is located in Tel Aviv, Israel.-Establishment:...
  
  , Israeli record label
• Primary school, a school providing primary education
• Primary source
  Primary source
  Primary source is a term used in a number of disciplines to describe source material that is closest to the person, information, period, or idea being studied....