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

The Colorescience Barrier Pro Serum Spray hydrates, strengthens the skin barrier, and promotes vitamin D production for a healthy, even-toned complexion year-round. —Emma Greene, InStyle, 10 Jan. 2026

Turtles, like all reptiles, require these rays to produce vitamin D and promote skeletal health. —Bestreviews, Chicago Tribune, 9 Jan. 2026

Some studies have found that using calcium and vitamin D supplements is safe in moderation, particularly for older adults. —Maggie O'Neill, Health, 9 Jan. 2026

In the analysis, vitamin D supplementation increased the likelihood of returning from prediabetes to normal blood sugar levels by 27% compared with placebo. —Fran Kritz, Verywell Health, 8 Jan. 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