vitamin D

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vitamin D

Wikipedia

From vitamin +‎ D (“4th letter”). From being the fourth vitamin discovered. Coined in 1922 by Elmer McCollum, who discovered the vitamin.

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vitamin D (uncountable)

1. (biochemistry) Any of a number of fat-soluble vitamins, required for normal bone development and that prevents rickets; can be manufactured in the skin on exposure to sunlight.
2. (slang, humorous, somewhat vulgar) A dick (“penis”), especially in a sexual context.

   Synonyms: see Thesaurus:penis

• vit. D (abbreviation)

• steroid
• hormone