n.
Pronunciation: ( ˌ ) ə r- ' gäs-t ə - ˌ ro ̇ l, - ˌ r ō l
Function: noun
Etymology: International Scientific Vocabulary
Date: 1906
: a crystalline steroid alcohol C 28 H 44 O that occurs especially in yeast, molds, and ergot and is converted by ultraviolet irradiation ultimately into vitamin D 2