[ proh-tuh-zoh-uh ]
/ ˌproʊ təˈzoʊ ə /


a major grouping or superphylum of the kingdom Protista, comprising the protozoans.

Origin of Protozoa

From New Latin, dating back to 1825–35; see origin at proto-, -zoa

Definition for protozoa (2 of 3)

[ proh-tuh-zoh-uh n ]
/ ˌproʊ təˈzoʊ ən /

noun, plural pro·to·zo·ans, (especially collectively) pro·to·zo·a [proh-tuh-zoh-uh] /ˌproʊ təˈzoʊ ə/.

any of a diverse group of eukaryotes, of the kingdom Protista, that are primarily unicellular, existing singly or aggregating into colonies, are usually nonphotosynthetic, and are often classified further into phyla according to their capacity for and means of motility, as by pseudopods, flagella, or cilia.


of, relating to, or characteristic of a protozoan.

Origin of protozoan

First recorded in 1860–65; Protozo(a) + -an

Definition for protozoa (3 of 3)

[ proh-tuh-zoh-on, -uh n ]
/ ˌproʊ təˈzoʊ ɒn, -ən /

noun, plural pro·to·zo·a [proh-tuh-zoh-uh] /ˌproʊ təˈzoʊ ə/.

Origin of protozoon

singular of Protozoa Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Examples from the Web for protozoa

British Dictionary definitions for protozoa

/ (ˌprəʊtəˈzəʊən) /

noun plural -zoa (-ˈzəʊə) or -zoans

Also called: protozoon (ˌprəʊtəˈzəʊɒn) plural -zoa any of various minute unicellular organisms formerly regarded as invertebrates of the phylum Protozoa but now usually classified in certain phyla of protoctists. Protozoans include flagellates, ciliates, sporozoans, amoebas, and foraminifers

adjective Also: protozoic

of or relating to protozoans

Word Origin for protozoan

C19: via New Latin from Greek proto- + zoion animal
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

Medical definitions for protozoa (1 of 2)

[ prō′tə-zōə ]


Plural ofprotozoan

Medical definitions for protozoa (2 of 2)

[ prō′tə-zōən ]

n. pl. pro•to•zo•a (-zōə)

Any of a group of single-celled, usually microscopic, eukaryotic organisms, such as amoebas, ciliates, flagellates, and sporozoans.

Other words from protozoan

pro′to•zoan null null adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for protozoa

[ prō′tə-zōən ]

Plural protozoans protozoa

Any of a large group of one-celled organisms (called protists) that live in water or as parasites. Many protozoans move about by means of appendages known as cilia or flagella. Protozoans include the amoebas, flagellates, foraminiferans, and ciliates. Their traditional classification as the subkingdom Protozoa is still used for convenience, but it is now known that protozoans represent several evolutionarily distinct groups. See more at protist.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for protozoa

[ (proh-tuh-zoh-uh) ]

Single-celled animals, such as amoebas, that are the most primitive form of animal life. In modern biology, they are classified in the kingdom of Protoctista rather than in the animal kingdom. (See Linnean classification.)

notes for protozoa

Some protozoa are parasites and may be pathogenic, causing diseases such as malaria and dysentery.
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.