Definition of "ergosterol" [ergosterol]

• A crystalline sterol, C28H43OH, synthesized by yeast from sugars or derived from ergot and converted to vitamin D2 when exposed to ultraviolet radiation. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "In addition, and especially important to its effectiveness as a remedy for ulcers and running sores, it is a rich source of ergosterol, which is converted by the sun's ultraviolet rays into vitamin D."
• "" And Amanda would answer, "The label states that this carton contains activated ergosterol."
• "Jimmy, I'm not sure about this activated ergosterol."