diatom

noun

di·​a·​tom ˈdī-ə-ˌtäm 

: any of a class (Bacillariophyceae) of minute planktonic unicellular or colonial algae with silicified skeletons that form diatomaceous earth

Examples of diatom in a Sentence

Recent Examples on the Web

Analysis shows these birds had ingested high amounts of domoic acid, from a diatom called pseudo-nitzschia, the same chemical that’s poisoned thousands of marine mammals in California this year alone. —Suwanna Gauntlett Upjohn, Forbes.com, 25 June 2025

The tiny diatom cells have regained full biological activity despite thousands of years beneath the seafloor without light or oxygen, according to the paper, published in the ISME Journal. —Julia Jacobo, ABC News, 1 Apr. 2025

The diatom species Skeletonema marinoi was the only phytoplankton species revived from the samples. —Julia Jacobo, ABC News, 1 Apr. 2025

Some, such as diatoms, can consume dissolved organic nutrients directly from the water. —Asher Elbein, WIRED, 2 Mar. 2025

Word History

Etymology

ultimately from Greek diatomos cut in half, from diatemnein to cut through, from dia- + temnein to cut — more at tome

First Known Use

1845, in the meaning defined above

Rhymes for diatom

• intercom
• aplomb
• balaam
• cocom
• embalm
• islam
• pogrom
• salaam
• sitcom
• balm
• bom
• bomb

Kids Definition

diatom

noun

di·​a·​tom ˈdī-ə-ˌtäm 

: any of a class of minute floating single-celled or colonial algae that are common in fresh and salt water and have a cell wall of silica that remains as a skeleton after death

diatomaceous

ˌdī-ət-ə-ˈmā-shəs

adjective

Medical Definition

diatom

noun

di·​a·​tom ˈdī-ə-ˌtäm 

: any of a class (Bacillariophyceae) of minute planktonic unicellular or colonial algae with silicified skeletons that form diatomite