Editing Primary (section)

==Science and mechanics==
* [[Primary (astronomy)]], the larger of two co-orbiting bodies
* [[Primary (chemistry)]], term used in organic chemistry
* Primary, the oldest period in the [[Geologic time scale]] (obsolete), combining the [[Precambrian]] and [[Paleozoic]]
* Primary, a stage in a [[nuclear weapon design|thermonuclear explosive]]
* [[Primary circuit]], electrical circuit in a transformer that receives current, as opposed to secondary circuit
* [[Primary field]],  type of field in conformal field theory
* [[Primary mirror]],  principal light-gathering surface of a reflecting telescope
* Primary [[power line]], electric power transmission line fed to or from a transformer
* [[Primary feathers]], flight feathers attached to the manus ("hand") in the wings of birds
* [[Primary color]]