earthwormPronunciation: /ˈəːθwəːm/Translate earthworm | into German | into Italian | into Spanish Definition of earthworm noun a burrowing annelid worm that lives in the soil, important in aerating and draining the soil and in burying organic matter. Family Lumbricidae, class Oligochaeta: Lumbricus, Allolobophora, and other genera earthworm in other Oxford dictionaries Definition of earthworm in the US English dictionary