primary

adjective

• 1of chief importance; principal:the government’s primary aim is to see significant reductions in unemployment

• 2earliest in time or order of development:the primary stage of their political education
• not derived from, caused by, or based on anything else:the research involved the use of primary source materials in national and local archives

• 3of or relating to education for children between the ages of about five and ten:a primary school

• 4 Biology & Medicine belonging to or directly derived from the first stage of development or growth:a primary bone tumor

• 5 (Primary) Geologyformer term for Paleozoic.

• 6relating to or denoting the input side of a device using electromagnetic induction, especially in a transformer.

• 7 Chemistry (of an organic compound) having its functional group located on a carbon atom that is bonded to no more than one other carbon atom.
• (chiefly of amines) derived from ammonia by replacement of one hydrogen atom by an organic group.

noun (plural primaries)

• 1 (also primary election) a preliminary election to appoint delegates to a party conference or to select the candidates for a principal, especially presidential, election.

• 2a primary color.
• Ornithology a primary feather.
• Astronomy the body orbited by a smaller satellite or companion.
• a primary coil or winding in an electrical transformer.

• 3 (the Primary) Geology, dated the Primary or Paleozoic era.