Is it ensure, insure, or assure?
mid-15c., "controller, prime mover," from Latin motor, literally "mover," agent noun from past participle stem of movere "to move" (see move (v.)). From 15c. as "controller, prime mover" (in reference to God); sense of "agent or force that produces mechanical motion" is first recorded 1660s; that of "machine that supplies motive power" is from 1856. First record of slang motor-mouth "fast-talking person" is from 1970.
1896, from motor (n.). Related: Motored; motoring.
motor mo·tor (mō'tər)
Causing or producing motion.
Of or being nerves that carry impulses from the nerve centers to the muscles.
Involving or relating to movements of the muscles.
Of or relating to an organism's overt reaction to a stimulus.
An amphetamine, esp Methedrine2; speed: ''What's motor? Speed?'' ''Un huh'' (1990s+ Narcotics)verb