Main Entry: di·a·tom

Pronunciation: \ˈdī-ə-ˌtäm\

Function: noun

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

Date: 1845

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