protist

American  

[proh-tist] / ˈproʊ tɪst /

noun

Microbiology

1. any of various one-celled organisms, classified in the kingdom Protista, that are either free-living or aggregated into simple colonies and that have diverse reproductive and nutritional modes, including the protozoans, eukaryotic algae, and slime molds: some classification schemes also include the fungi and the more primitive bacteria or may distribute the organisms between the kingdoms Plantae and Animalia according to dominant characteristics.

---

protist British  

/ ˈprəʊtɪst /

noun

1. (in some classification systems) any organism belonging to the kingdom Protista, originally including bacteria, protozoans, algae, and fungi, regarded as distinct from plants and animals. It was later restricted to protozoans, unicellular algae, and simple fungi See also protoctist

---

protist Scientific  

/ prō′tĭst /

1. Any of a large variety of usually one-celled organisms belonging to the kingdom Protista (or Protoctista). Protists are eukaryotes and live in water or in watery tissues of organisms. Some protists resemble plants in that they produce their own food by photosynthesis, while others resemble animals in consuming organic matter for food. Protist cells are often structurally much more elaborate than the cells of multicellular plants and animals. Protists include the protozoans, most algae, diatoms, oomycetes, and the slime molds.

2. Also called protoctist

3. See Table at taxonomy

---

Other Word Forms

Derived Forms

• protistic
  adjective
• protistan
  adjective

Etymology

Origin of protist

First recorded in 1870–75; from German Protist (masculine singular), from New Latin Protista (neuter plural) name of the kingdom, from Greek prṓtistos (masculine singular) “the very first,” superlative of prôtos “first”; see proto-

Compare meaning

How does protist compare to similar and commonly confused words? Explore the most common comparisons:

• protist vs. Protozoa

Example Sentences

"The definition of a protist is loose -- essentially it is any eukaryotic organism which is not an animal, plant, or fungus," said Dr. McGowan.

From Science Daily • May 7, 2026

"U-ExM is transforming how we explore protist ultrastructure," said co-first author Armando Rubio Ramos, a Postdoctoral Fellow at the University of Geneva.

From Science Daily • Nov. 2, 2025

Although kelp behaves and looks like a plant, it’s a protist, the same group as single-cell amoebas.

From Seattle Times • Jun. 8, 2023

Chlamydomonas is a simple, unicellular chlorophyte with a pear-shaped morphology and two opposing, anterior flagella that guide this protist toward light sensed by its eyespot.

From Textbooks • Jan. 1, 2015

In turn, the corals provide the protist with a protected environment and the compounds needed for photosynthesis.

From Textbooks • Jan. 1, 2015