Wā'ter-pĕp'per, n.

n. (Bot.) (a.) One of an order of annual marsh-plants, of which the genus Elatine is the type. Some species possess a considerable degree of acridity. Baird. (b.) A plant of the genus Polygonum (P. hydropiper), a hot, acrid plant, reputed to be a powerful diuretic, and the leaves of which act as vesicants. Baird.