Ar'il or A-ril'lus, n.

n. [N. Lat. arillus, Fr. arille, Sp. arillo; of L. Lat. arilli, dry grapes, from aridus, dry.] (Bot.) An exterior covering, forming a false coat or appendage to a seed, as the loose, transparent bag inclosing the seed of the white water-lily: the mace of the nutmeg is also an aril. Gray.