gall waspEnglishOxford New American Dictionarygall wasp /ɡôl wäsp, ɡɔl wɑsp/ ▸ noun a small winged insect that is similar to an ant in appearance. The female lays its egg in plant tissue, which swells to form a gall when the larva hatches. Superfamily Cynipoidea, order Hymenoptera: several genera.