amoeba

noun

amoe·​ba ə-ˈmē-bə How to pronounce amoeba (audio)
variants or less commonly ameba
plural amoebas or amoebae also amebas or amebae ə-ˈmē-(ˌ)bē How to pronounce amoeba (audio)
: any of a large genus (Amoeba) of naked rhizopod protozoans with lobed and never anastomosing pseudopodia, without permanent organelles or supporting structures, and of wide distribution in fresh and salt water and moist terrestrial environments
broadly : a naked rhizopod or other amoeboid protozoan
amoebic adjective
or less commonly amebic
ə-ˈmē-bik

Illustration of amoeba

Illustration of amoeba
  • 1 pseudopodium
  • 2 nucleus
  • 3 contractile vacuole
  • 4 food vacuole

Examples of amoeba in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The North Carolina Department of Health and Human Services is still investigating numerous possible sources of the brain-eating amoeba, State Public Health Veterinarian Carl Williams said. — Charlotte Observer, 3 Sep. 2026 Officials added that people cannot become infected with Naegleria fowleri by swallowing contaminated water; however, the amoeba can enter the body when it is forcefully introduced, such as through the nose into the brain. — Angel Saunders, PEOPLE, 2 Sep. 2026 The amoeba can live in warm freshwater, like ponds, lakes and rivers. — Emily Shapiro, ABC News, 1 Sep. 2026 The amoeba is most active in the months that the water temperature stays elevated. — Melissa Rudy, FOXNews.com, 1 Sep. 2026 See All Example Sentences for amoeba

Word History

Etymology

New Latin, genus name, from Greek amoibē change, from ameibein to change — more at migrate

First Known Use

1822, in the meaning defined above

Time Traveler
The first known use of amoeba was in 1822

Rhymes for amoeba

See All Rhymes for amoeba

Browse Nearby Words

amobarbital
amoeba
amoeba disease
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Cite this Entry

“Amoeba.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/amoeba. Accessed 4 Sep. 2026.

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Kids Definition

amoeba

noun
amoe·​ba
variants also ameba
ə-ˈmē-bə
plural amoebas or amoebae -(ˌ)bē How to pronounce amoeba (audio)
: any of a large genus of protozoans that have no permanent cell organs or structures, that change shape to form temporary lobes for moving and taking in food, and that are widespread in fresh and salt water and in moist soils
amoebic
-bik How to pronounce amoeba (audio)
adjective

Medical Definition

amoeba

noun
amoe·​ba
ə-ˈmē-bə
1
capitalized : a large genus of naked rhizopod protozoans that have lobed and never anastomosing pseudopodia and are widely distributed in fresh and salt water and moist terrestrial environments
2
also ameba plural amoebas or amoebae -(ˌ)bē How to pronounce amoeba (audio) also amebas or amebae : a protozoan of the genus Amoeba
broadly : an amoeboid protozoan (as a naked rhizopod)
amebic adjective
or amoebic
-bik How to pronounce amoeba (audio)

More from Merriam-Webster on amoeba

Britannica.com: Encyclopedia article about amoeba

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