The Collaborative International Dictionary of English v.0.48:

corticosteroid \corticosteroid\ n.
   a steroid compound produced by the adrenal cortex, or a
   synthetic analog of such a compound.

   Syn: corticoid.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

corticosteroid
    n 1: a steroid hormone produced by the adrenal cortex or
         synthesized; administered as drugs they reduce swelling and
         decrease the body's immune response; "adrenal cortical
         steroids are used to treat many different conditions" [syn:
         corticosteroid, corticoid, adrenal cortical steroid]