tachysterol
noun
ta·chys·ter·ol
| \ ta-ˈkist-ə-ˌrȯl
, -ˌrōl
\
, -ˌrōl
\
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