Definition of "protist" [pro•tist]

• Any of a group of eukaryotic organisms belonging to the kingdom Protista according to some widely used modern taxonomic systems. The protists include a variety of unicellular, coenocytic, colonial, and multicellular organisms, such as the protozoans, slime molds, brown algae, and red algae. (noun)
• A unicellular protoctist in taxonomic systems in which the protoctists are considered to form a kingdom. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The Toxoplasma bacteria protist is shed in cat feces, which are eaten by rats; infected rats become fearless in the presence of cats, which makes them easier to catch, which, in turn spreads the disease to new cats."
• "They discovered a heterotrophic algae, in reality a protist, that is"
• "Simpson (1961: 117, 165) emphasized this by pointing out that an unbroken lineage could be traced from man back to protist ancestors, and any delimitation that represents a point in time means that an individual organism “could belong to one species one instant and to another species the next instant.”"