motive (adj.) Look up motive at Dictionary.com
late 14c., from Old French motif "moving" or directly from Medieval Latin motivus "moving, impelling," from past participle stem of movere "to move" (see move (v.)).
motive (n.) Look up motive at Dictionary.com
mid-14c., "something brought forward," from Old French motif "will, drive, motivation," noun use of adjective, literally "moving," from Medieval Latin motivus "moving, impelling," from Latin motus "a moving, motion," past participle of movere "to move" (see move (v.)). Meaning "that which inwardly moves a person to behave a certain way" is from early 15c.