1 used to refer to any of various types of very small animals with one cell; involving or relating to this type:
Toxoplasmosis is an infection caused by a protozoan parasite found in undercooked meat.
When the temperature reached 32-degrees-F all protozoan activity ceased.
2 a very small organism with only one cell
The protozoan that causes malaria can penetrate the gut wall and ultimately migrate to the mosquito's salivary gland, where it is injected into the mosquito's next victim.
Isosporiasis is caused by Isospora belli, a protozoan belonging to the family Apicomplexa.
These single-celled protozoa get shuttled among people and animals by several species of insects.
Cryptosporidium are protozoan parasites.
They studied 30 widely differing types of marine bacteria that were all readily eaten by protozoan predators.
It should be noted, however, that protozoan and myxozoan parasites were not recorded in most studies.
Since its description, the lifecycle of this protozoan parasite has eluded discovery.