roton do (roton do)

[ In analogy with this [Hamilton's use of the word vector, I propose to use the name rotor (short for rotator) to mean a quantity having magnitude, direction, and position, of which the simplest type is a velocity of rotation about a certain axis. A rotor will be geometrically represented by a length proportional to its magnitude measured upon its axis in a certain sense. W. K. Clifford, Lond. Math. Soc. Proc., 1873, p. 351 [ME.,