0 any of various types of very small animals with one cell: --
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 --
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.
We kunnen het stap voor stap voltooien, hoe lang de weg ook is en het kan niet worden voltooid, hoe kort de weg ook is, als je niet eens je voetafdruk markeert.