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noun, plural a·moe·bas, a·moe·bae [uh-mee-bee] /əˈmi bi/.
  1. ameba.


or a·moe·ba

noun, plural a·me·bas, a·me·bae [uh-mee-bee] /əˈmi bi/.
  1. any of numerous freshwater, marine, or parasitic one-celled protozoa of the order Amoebida, characterized by a granular nucleus surrounded by a jellylike mass of cytoplasm that forms temporary extensions, or pseudopodia, by which the organism moves, engulfs food particles, and forms food vacuoles.
  2. a protozoan of the genus Amoeba, inhabiting bottom vegetation of freshwater ponds and streams: used widely in laboratory studies.

Origin of ameba

< New Latin amoeba < Greek amoibḗ change, alternation, akin to ameíbein to exchange
Related formsa·me·ba·like, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for amoeba


US ameba

noun plural -bae (-biː) or -bas
  1. any protozoan of the phylum Rhizopoda, esp any of the genus Amoeba, able to change shape because of the movements of cell processes (pseudopodia). They live in fresh water or soil or as parasites in man and animals
Derived Formsamoebic or US amebic, adjective

Word Origin

C19: from New Latin, from Greek amoibē change, from ameibein to change, exchange


noun plural -bae (-biː) or -bas
  1. the usual US spelling of amoeba
Derived Formsamebic, adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for amoeba


1855, from Modern Latin Amoeba, genus name (1841), from Greek amoibe "change," related to ameibein "to change, exchange," from PIE *e-meigw-, extended form of root *mei- "to change, go, move" (see mutable). So called for its constantly changing shape. Related: Amoebaean; amoebic.

Online Etymology Dictionary, © 2010 Douglas Harper

amoeba in Medicine


  1. Variant ofameba


n. pl. a•moe•bas
  1. A genus of protozoa of the class Sarcodina or Rhizopoda.
  2. Any of several genera of protozoa that are parasitic in humans, especially Entamoeba.


n. pl. a•me•bas
  1. A protozoa of the genus Amoeba and of related genera, occurring in soil and water and parasitic in animals.

amoeba in Science


Plural amoebas amoebae (ə-mē)
  1. Any of various one-celled aquatic or parasitic protozoans of the genus Amoeba or related genera, having no definite form and consisting of a mass of protoplasm containing one or more nuclei surrounded by a flexible outer membrane. Amoebas move by means of pseudopods.


  1. Another spelling of amoeba.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

amoeba in Culture



An animal composed of only one cell that has no fixed shape. It is the best known of the single-celled animals, or protozoa.


The term amoeba is sometimes used to refer to something with an indefinite, changeable shape.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.