turbellarian
noun
tur·bel·lar·i·an ˌtər-bə-ˈler-ē-ən 
: any of a class (Turbellaria) of mostly aquatic and free-living flatworms (such as a planarian)
turbellarian adjective
Word History
Etymology
ultimately from Latin turbellae (plural) bustle, stir, diminutive of turba confusion, crowd; from the tiny eddies created in water by the cilia
First Known Use
1883, in the meaning defined above
Medical Definition
turbellarian
noun
tur·bel·lar·i·an -ˈler-ē-ən, -ˈlar-
: any flatworm of the class Turbellaria