1. adjective
a) Succeeding next in order to the first; of second place, origin, rank, rank, etc.; not primary; subordinate; not of the first order or rate.
Yellow is a secondary light color, though a primary CMYK color.
b) Acting by deputation or delegated authority; as, the work of secondary hands.
2. noun
b) An act of issuing more stock by an already publicly traded corporation.
Wikipedia foundation.