Merriam-Webster Collegiate Dictionary - motor

 I. noun  Etymology: Latin, from movere to move  Date: 1586  1. one that imparts motion; specifically prime mover  2. any of various power units that develop energy or impart motion: as  a. a small compact engine  b. internal combustion engine; especially a gasoline engine  c. a rotating machine that transforms electrical energy into mechanical energy  3. ~ vehicle; especially automobile  • ~dom noun  • ~less adjective  II. adjective  Date: 1824  1.  a. causing or imparting motion  b. of, relating to, or being a ~ neuron or a nerve containing ~ neurons ~ fiber  c. of, relating to, concerned with, or involving muscular movement ~ areas of the brain  2.  a. equipped with or driven by a ~  b. of, relating to, or involving an automobile  c. designed for ~ vehicles or ~ists  III. verb  Date: 1896  intransitive verb  1. to travel by automobile ; drive  2. to move or proceed at a vigorous steady pace ~ed down the field for a touchdown  transitive verb to transport by automobile