contributory

Etymology

From earlier contributary, from Middle English contributarie, from con- + tributarie after Middle French contributaire.

adj

1. Of, pertaining to, or involving a contribution.
2. Tending to contribute to a result.
3. (obsolete) Paying tribute, tributary.

noun

1. A person or thing that contributes.
   The response to firing is remarkable, and though the 280 lb. pressure seems more in the nature of a reserve for emergencies than a continuous working figure, even with the present-day apology for coal it seldom fell below 250 lb., and could always be brought up to blowing-off point with little difficulty. To this liveliness of steaming the thermic syphons are doubtless the chief contributory. 1947 January and February, Cecil J. Allen, “British Locomotive Practice and Performance”, in Railway Magazine, page 39