primary

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective First or highest in rank or importance; principal. synonym: chief.
• adjective Occurring first in time or sequence; earliest.
• adjective Of or relating to primary schools.
• adjective Not derived from anything else; basic or original.
• adjective Immediate; direct.
• adjective Geology Characteristic of or existing in a rock at the time of its formation.
• adjective Of or relating to a primary color or colors.
• adjective Having a word root or other linguistic element as a basis that cannot be further analyzed or broken down. Used of the derivation of a word or word element.
• adjective Referring to present or future time. Used as a collective designation for various present and future verb tenses in Latin, Greek, and Sanskrit.
• adjective Of or relating to primary stress.
• adjective Electronics Of, relating to, or constituting an inducting current, circuit, or coil.
• adjective Of, relating to, or designating the main flight feathers projecting along the outer edge of a bird's wing.
• adjective Of or relating to agriculture, forestry, the industries that extract natural materials from the earth, or the products so obtained.
• adjective Relating to, or having a carbon atom that is attached to only one other carbon atom in a molecule.
• adjective Relating to the replacement of only one of several atoms or groups in a compound, such as an amine in which one valence of the functional group is taken by a carbon atom.
• adjective Botany Of, relating to, or derived from a primary meristem.
• noun One that is first in time, order, or sequence.
• noun One that is first or best in degree, quality, or importance.
• noun One that is fundamental, basic, or elemental.
• noun A meeting of the registered voters of a political party for the purpose of nominating candidates and for choosing delegates to their party convention.
• noun A preliminary election in which the registered voters of a political party nominate candidates for office.
• noun A primary color.
• noun A primary flight feather.
• noun Electronics An inducting current, circuit, or coil.
• noun A celestial body, especially a star, relative to other bodies in orbit around it.
• noun The brighter of two stars that make up a binary star.

from The Century Dictionary.

• The body of the bark which lies between the epidermis and stele (central cylinder) in the stems of phanerogams, as also the corresponding zone in the root. In this sense sometimes simply cortex. Strasburger.
• noun In electricity: In an alternating-current transformer, induction-motor, or other apparatus containing two circuits in inductive relation to one another, that circuit which receives power from the impressed electromotive force.
• noun Sometimes, in an alternating-current transformer, the high potential coil, the low potential coil being the secondary.
• noun In physiological optics, one of the primary colors or primary color-sensations.
• noun A lesion of the initial stage of syphilis, a chancre: usually in the plural.
• noun In Echinodermata: In echinoids, a plate which extends from the outer edge of an ambulacral area to the median suture of that area.
• noun In echinoids, a spine of the largest order extending beyond the shorter secondaries.
• noun In crinoids, according to Bather's terminology, any one of those plates which are first developed in the ontogeny and phylogeny, including the abactinal system of columnals, cirrals, infrabasals, basals, radials, brachials, pinnulars, and the actinal system of orals and ambulacrals.
• noun In the Echinoidea, one of the large and completely developed tubercles on the surface of the test, which serve as articulating bases for the spines.
• First or highest in rank, dignity, or importance; chief; principal.
• First in order of being, of thought, or of time; original; primitive; first.
• First or lowest in order of growth or development; elementary; preparatory.
• First in use or intention; radical; original: as, the primary sense of a word.
• In ornithology, of the first rank or order among the flight-feathers or remiges of the wing; situated upon the manus or pinion-bone, as a feather: correlated with secondary and tertiary or tertial. See II.
• In geology, lowest in the sequence of geological formations: said of rocks.
• noun That which stands first or highest in rank or importance, as opposed to secondary; that to which something else is subordinate.
• noun In ornithology, one of the remiges, flight-feathers, or large quills which are situated upon the manus. pinion-bone, or distal segment of the wing.