Definition

1. Noun:
   • A diverse minute acellular or unicellular organism, usually nonphotosynthetic: A protozoon is a single-celled or non-cellular microscopic organism belonging to the kingdom Protista. They are typically heterotrophic, meaning they obtain nutrients by ingesting other organisms or organic matter, rather than through photosynthesis.

Usage Examples

• Noun:
  • The pond water was teeming with various protozoa. (The pond water was full of different single-celled organisms.)
  • Malaria is caused by a protozoon of the genus Plasmodium. (Malaria is caused by a specific type of single-celled parasite.)
  • Under the microscope, we observed a protozoon capturing its food. (Using the microscope, we saw a unicellular organism catching something to eat.)

Advanced Usage

• Scientific Context: The term is often used in biology, medicine, and ecology to describe these simple eukaryotic organisms.
  • The study of pathogenic protozoa is crucial for tropical medicine.
• Plural Form: The most common plural is "protozoa." The form "protozoons" is also correct but less frequent.
  • Protozoa are found in almost every possible habitat.

Variants and Related Words

• Protozoan (noun/adjective): An alternative term for protozoon. As an adjective, it describes something related to protozoa.
  • Protozoan infections can be difficult to treat. (Infections caused by these organisms can be hard to cure.)
• Protozoology (noun): The branch of zoology that studies protozoa.
• Protozoic (adjective): Relating to or characteristic of protozoa.

Synonyms

• Microorganism: A very small living thing, which can include bacteria and protozoa.
• Unicellular organism: An organism consisting of a single cell.
• Protist: A member of the kingdom Protista, which includes protozoa and some algae.

Notes on Meaning

• The term specifically refers to eukaryotic, typically motile, single-celled organisms. It is distinct from bacteria, which are prokaryotic.
• While often microscopic, some protozoa are large enough to be seen with the naked eye.
• The classic definition describes them as animal-like protists, contrasting with plant-like protists (algae).

Noun

1. any of diverse minute acellular or unicellular organisms usually nonphotosynthetic