1. noun
a) A standard measure of a quantity.
The centimetre is a unit of length.
b) An organized group comprising people and/or equipment.
He was a member of a special police unit.
Syn: identity element, unit element
2. adjective
a) For each unit.
We have to keep our unit costs down if we want to make a profit.
b) Having a size or magnitude of one.
All solutions lie within the unit disc centered at the origin.
Wikipedia foundation.