tachysterol

noun
ta·​chys·​ter·​ol | \ ta-ˈkist-ə-ˌrȯl How to pronounce tachysterol (audio) , -ˌrōl How to pronounce tachysterol (audio) \

Medical Definition of tachysterol

: an oily liquid alcohol C28H43OH isomeric with ergosterol that is formed by ultraviolet irradiation of ergosterol or lumisterol and that on further irradiation yields vitamin D2 — see dihydrotachysterol