A unit of fluidity, the opposite of viscosity. The unit, pronounced "ree", was introduced by the American chemist F.C. Bingham in 1928; he defined it as the reciprocal of the centipoise. However, it came to be used instead as the reciprocal of the poise itself, so the fluidity of a substance in rhes is 1 divided by its dynamic viscosity in poise. in SI units, the rhe equals 10 per pascal-second (10 (Pa·s)-1). The name of the unit comes from the Greek rhein, to flow