What is the term for a protist that uses a flagellum to move?

What you're looking for is the specific genus. The genus (or term) for a protist that uses a flagellum to move is Euglena.

Euglena is a member of the class Euglenoidea. This group consists of 54 genera and more than 800 species. The class Euglenoidea is made up of flagellates - a cell or organism with one or more whip-like organelles called flagella.

Below are some interesting facts about Euglena:

1. Species of Euglena were among the first protists to be observed under a microscope.


2. Since Euglena have features of both animals and plants, early taxonomists found them difficult to classify. It wasn't until 1841 that the criteria for being a Euglena was established, with the addition of the filament flagelliform to its description.

I hope this answer was informative!