vitamin D

noun

: any or all of several fat-soluble vitamins chemically related to steroids, essential for normal bone and tooth structure, and found especially in fish-liver oils, egg yolk, and milk or produced by activation (as by ultraviolet irradiation) of sterols: such as

a

or vitamin D₂

-ˈdē-ˈtü 

: calciferol

b

or vitamin D₃

-ˈdē-ˈthrē 

: cholecalciferol

Examples of vitamin D in a Sentence

Recent Examples on the Web

These mushrooms are often grown in full sunlight or under UV lamps, which help increase their vitamin D levels. —Lana Barhum, Verywell Health, 21 Apr. 2026

The main health benefit of sunshine is vitamin D, which supports strong bones, immune health, and overall wellness. —Allison Forsyth, Health, 20 Apr. 2026

Light triggers vitamin D production and is a crucial driver of circadian rhythms. —Maria Godoy, NPR, 13 Apr. 2026

Milk is packed with calcium, vitamin D, and protein, which strengthen bones, support muscles, and reduce osteoporosis risk. —Kirsten Nunez, Martha Stewart, 4 Apr. 2026

Word History

First Known Use

circa 1921, in the meaning defined above

Rhymes for vitamin D

• abc
• absentee
• addressee
• adoptee
• agouti
• allottee
• amphorae
• amputee
• apc
• apogee
• appointee
• assessee

Kids Definition

vitamin D

noun

: any of several vitamins that are needed for normal bone and tooth structure, and are found especially in fish-liver oils, egg yolk, and milk or are produced in response to ultraviolet light

Medical Definition

vitamin D

noun

: any or all of several fat-soluble vitamins chemically related to steroids, essential for normal bone and tooth structure, and found especially in fish-liver oils, egg yolk, and milk or produced by activation (as by ultraviolet irradiation) of sterols: as

a

: calciferol

b

: cholecalciferol

called also sunshine vitamin