hydrocortisonePronunciation: /ˌhʌɪdrə(ʊ)ˈkɔːtɪzəʊn/Definition of hydrocortisone noun [mass noun] Biochemistry a steroid hormone produced by the adrenal cortex and used medicinally to treat inflammation resulting from eczema and rheumatism. hydrocortisone in other Oxford dictionaries Definition of hydrocortisone in the US English dictionary