dexa·meth·a·sone \ˌdeksəˈmethəˌsōn, -ˌzōn\noun (-s) Etymology:dexa- (blend of deca- and hexa-) + methyl + -a- (perhaps from pregnane) + -sone (as in cortisone) : a synthetic glucocorticoid C22H29FO5 used especially as an anti-inflammatory and antiallergic agent