The building blocks of English

Affixes

rheo-

Current or flow.

Greek rheos, stream.

Rheology is the branch of physics that deals with the deformation and flow of matter, especially the non-Newtonian flow of liquids and the plastic flow of solids; a rheometer is an instrument for measuring the flow of fluids, especially blood; a rheostat is an electrical instrument used to control a current by varying the resistance; rheotaxis is the property of a living organism of responding to the stimulus of a flow of water.