dex·a·meth·a·sone 
(dĕk′sə-mĕthə-sōn′, -zōn′)
(dĕk′sə-mĕthə-sōn′, -zōn′)n.
A synthetic glucocorticoid, C22H29FO5, used in the treatment of insufficient adrenocortical function, a variety of inflammatory disorders such as arthritis and ulcerative colitis, and certain types of cancer.
[dexa- (blend of DECA- + HEXA-) + METH(YL) + alteration of (PREDN)IS(OL)ONE.]