international unit

noun

: a quantity of a biologically active substance (such as a vitamin) that produces a particular biological effect agreed upon as an international standard

Examples of international unit in a Sentence

Recent Examples on the Web

It's typically measured in international units (IU) or micrograms (mcg), and dosages aren't broken down by vitamin D type. —Lindsey Desoto, Health, 24 Nov. 2025

In research studies, the dose of vitamin D has ranged from 800 to 4,000 IU (international units) per day. —Morgan Pearson, Verywell Health, 14 Nov. 2025

How much vitamin D your body needs depends on factors like age and pregnancy status, though most healthy adults require at least 600 international units (IU) daily. —Tom Gavin, EverydayHealth.com, 12 Nov. 2025

More than half of them required an initial dose of 5,000 international units (IU). —Angelica Stabile, FOXNews.com, 12 Nov. 2025

Word History

First Known Use

1921, in the meaning defined above

Rhymes for international unit

• lunate
• multiunit
• subunit

Medical Definition

international unit

noun

: the amount of specific physiological activity of a standardized preparation (as of a vitamin) that is agreed upon as an international standard especially for comparison with other biologicals containing the substance in impure form or with a related biologically active substance

also : the amount of the biologically active substance in the standard amount of the preparation producing this activity