dexamethasone UK /ˌdɛk.səˈmɛθ.ə.səʊn/US /ˌdɛk.səˈmɛθ.əˌsoʊn/ noun1 •A synthetic member of the glucocorticoid-class of steroid hormones, having the chemical formula C₂₂H₂₉FO₅, and used especially as an anti-inflammatory agent.Many dexamethasones act as anti-inflammatory agents. formsdexamethasones