| Noun | 1. | Notonecta undulata - predaceous aquatic insect that swims on its back and may inflict painful biteshemipteran, hemipteron, hemipterous insect, bug - insects with sucking mouthparts and forewings thickened and leathery at the base; usually show incomplete metamorphosis genus Notonecta, Notonecta - type genus of the Notonectidae: backswimmers |