Definition of diatom
: any of a class (Bacillariophyceae) of minute planktonic unicellular or colonial algae with silicified skeletons that form diatomaceous earth
Keep scrolling for more
Keep scrolling for more
Test Your Vocabulary
The Exceptions Quiz III
-
- Which of these words does not mean "nonsense"?

Test your vocabulary with our 10-question quiz!
TAKE THE QUIZ
Spell words. Make bears.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridged
Words at Play
Ask the Editors
Share diatom
Time Traveler for diatom
The first known use of diatom was in 1845
See more words from the same year