Webster’s Revised Unabridged Dictionary · 1913
Decrescent
De·cres′cent (dē·krĕs′sent), a. [L. decrescens, p. pr. of decrescere. See Decrease.] Becoming less by gradual diminution; decreasing; as, a decrescent moon.
De·cres′cent, n. (Her.) A crescent with the horns directed towards the sinister. Cussans.