Any of several types of internal combustion engine in which the power output is directly rotational.

plural of rotamer

of, pertaining to, or causing rotation; rotational / (obsolete) alternate or successive

plural of Rotarian

a disk with finger holes, used to enter numbers by rotating the disk forward and letting it slide back / a telephone with such a disk

(of a telephone) using a rotary dial, rather than push buttons

plural of axis of rotation

(physics) An interaction between a polarized electromagnetic pulse, such as a beam of light, and a magnetic field, in which the plane of polarization is rotated in proportion to the intensity of the component of the magnetic field in the direction of travel of the pulse.

plural of rotary

(chemistry) A piece of laboratory equipment used to gently evaporate solvents from a chemical solution in a temperature controlled environment.