Source : Webster's Revised Unabridged Dictionary (1913)

Motorize \Mo"tor*ize\ (m[=o]"t[~e]r*[imac]z), v. t. [Motor +
   -ize.]
   To substitute motor-driven vehicles, or automobiles, for the
   horses and horse-drawn vehicles of (a fire department, city,
   etc.). -- {Mo`tor*i*za"tion}, n.

Source : WordNet®

motorize
     v 1: equip with a motor vehicle; "The police around here are not
          motorized and patrol the streets on horseback"
     2: equip with a motor; "motorized scooters are now the rage"
     3: equip with armed and armored motor vehicles; "mechanize
        armies" [syn: {mechanize}, {mechanise}, {motorise}]