n. [ F. pimprenelle; cf. Sp. pimpinela, It. pimpinella; perh. from LL. bipinnella, for bipinnula two-winged, equiv. to L. bipennis; bis twice + penna feather, wing. Cf. Pen a feather. ] (Bot.) A plant of the genus Anagallis, of which one species (Anagallis arvensis) has small flowers, usually scarlet, but sometimes purple, blue, or white, which speedily close at the approach of bad weather. [ 1913 Webster ]

Water pimpernel. (Bot.) See Brookweed. [ 1913 Webster ]