"containing repetitions, characterized by or of the nature of repetition," 1805, from Latin repetit-, past-participle stem of repetere "do or say again" (see repeat (v.)) + -ive. Related: Repetitively; repetitiveness. Other adjectives, in addition to repetitious (1670s) included repetitionary (1720), repetitional (1720).
repetitional, repetitionary, repetitious, repetitive. With all these on record, repetition would seem to have a good stock of adjectives at need ; but few writers have the hardihood to use any of them. Repetitious is said to be 'common in recent American use' ; repetitive is perhaps the least avoided in England. [Fowler, 1926]