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di·a·tom

(dīə-tŏm′)

Any of various microscopic one-celled or colonial heterokonts of the class Bacillariophyceae that are photosynthetic, have a silica cell wall made up of two interlocking parts, and form an important component of phytoplankton.

[New Latin diatoma, from Greek diatomos, cut in half, from diatemnein, to cut in half : dia-, dia- + temnein, to cut; see tem- in the Appendix of Indo-European roots.]

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diatom

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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