Cortisone (/ˈkɔrtɨsoʊn/ or /ˈkɔrtɨzoʊn/ ; 17-hydroxy-11-dehydrocorticosterone) is a 21-carbon steroid hormone. It is one of the main hormones released by the adrenal gland in response to stress.ortisone (/ˈkɔrtɨsoʊn/ or /ˈkɔrtɨzoʊn/ ; 17-hydroxy-11-dehydrocorticosterone) is a 21-carbon steroid hormone. It is one of the main hormones released by the adrenal gland in response to stress.