1873, "act or process of furnishing with an incentive or inducement to action;" see motivate + -ion. Perhaps borrowed from German, where motivation is attested by 1854. Psychological use, "inner or social stimulus for an action," is from 1904.
we did not understand his motivation
his motivation was at a high level
motile
motility
motion
motionless
motivate
motivation
motivational
motivator
motive
motiveless
motley