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Pro·te·us (prōtē-əs, -tys)
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n.
Greek Mythology
A sea god who could change his shape at will.

[Latin Prōteus, from Greek, from prōtos, first (compare his epithet halios gerōn, Old Man of the Sea; see PER-1).]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
 
pro·te·us (prōtē-əs)
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n. pl. pro·te·i (-tē-ī)
Any of various gram-negative, rod-shaped bacteria of the genus Proteus, certain species of which are associated with human enteritis and urinary tract infections.

[New Latin Prōteus, genus name, from Latin, Proteus (the variability in the size of individual cells displayed by members of the genus being likened to the god's shape-shifting powers); see PROTEUS.]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
 

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.