omega-3

adjective

ome·​ga-3 ō-ˈmā-gə-ˈthrē 

-ˈmē-, 

-ˈme- 

: being or composed of polyunsaturated fatty acids that have the final double bond in the hydrocarbon chain between the third and fourth carbon atoms from the end of the molecule opposite that of the carboxyl group and that are found especially in fish, fish oils, green leafy vegetables, and some nuts and vegetable oils compare omega-6

omega-3 noun

Examples of omega-3 in a Sentence

Recent Examples on the Web

Nuts and fatty fishes, like salmon and sardines, contain omega-3 fatty acids, which are important for building the insulating sheaths that surround the nerve fibers that carry information from one brain cell to another. —Dana G. Smith, New York Times, 6 Jan. 2026

The omega-3 fatty acids in salmon may have an anti-inflammatory effect. —Julie Marks, Verywell Health, 6 Jan. 2026

Salmon also delivers plenty of protein and omega-3s, healthy fats that support your heart and brain. —Jenna Anderson, Health, 31 Dec. 2025

Some insist the drug must be paired with vitamin B12, omega-3, or a certain amino acid; others caution that dairy can reduce its effectiveness. —Tom Bartlett, The Atlantic, 19 Dec. 2025

Word History

First Known Use

1967, in the meaning defined above

Medical Definition

omega-3

adjective

ome·​ga-3 -ˈthrē 

variants also Omega-3

: being or composed of polyunsaturated fats that have the first double bond in the hydrocarbon chain occurring between the third and fourth carbon atoms from the end of the molecule most distant from the carboxylic acid group and that are found especially in fish, fish oils, green leafy vegetables, and some nuts and seeds

The two main omega-3 fatty acids in fish oil … appear to reduce the risk of dying from sudden cardiac arrest by about 30 percent.

—Nutrition Action Health Letter

compare omega-6

omega-3 noun

also Omega-3

Some plants, such as linseed, naturally produce an omega-3 called alpha-linolenic acid (ALA), and one way to increase the amount of omega-3 in our diet is to eat these plants …

—Andy Coghlan, New Scientist