Nouns

(n)motivation, motive, needthe psychological feature that arouses an organism to action toward a desired goal; the reason for the action; that which gives purpose and direction to behavior“we did not understand his motivation”, “he acted with the best of motives”
(n)motif, motivea theme that is repeated or elaborated in a piece of music
(n)motif, motivea design or figure that consists of recurring shapes or colors, as in architecture or decoration

Adjectives

(s)motive, motorcausing or able to cause motion“a motive force”, “motive power”, “motor energy”
(s)motivative, motive, motivatingimpelling to action“it may well be that ethical language has primarily a motivative function” (Arthur Pap), “motive pleas”, “motivating arguments”