A novel capillary-pipe rheometer is presented. The rheometer allows one to identify some abnormal properties of apparently Newtonian or non-Newtonian liquids both in the laminar and the turbulent flow range. A proposal for a new definition of a non-Newtonian fluid is given. In the author's opinion, such fluids as high-molecular polymer solutions and surfactant's solutions of very low concentrations should also be classified as non-Newtonian fluids.