bagworm /ˈbæɡ.wɜː(ɹ)m/ noun4 •Certain moths, in order Lepidoptera. •A bagworm moth, any member of the family Psychidae. •A Fall webworm (Hyphantria cunea, family Erebidae). •(nonstandard) An Eastern tent caterpillar (Malacosoma americanum, family Lasiocampidae). formsbagworms