An earthworm is a soil-dwelling terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class Oligochaeta. In classical systems, they were in the order of Opisthopora since the male pores opened posterior to the female pores, although the internal male segments are anterior to the female. Theoretical cladistic studies have placed them in the suborder Lumbricina of the order Haplotaxida, but this may change. Other slang names for earthworms include "dew-worm", "rainworm", "nightcrawler", and "angleworm". Larger terrestrial earthworms are also called megadriles as opposed to the microdriles in the semiaquatic families Tubificidae, Lumbricidae and Enchytraeidae. The megadriles are characterized by a distinct clitellum and a vascular system with true capillaries.

भूकृमि या केंच्वा एक स्थलीय अकशेरुकीय है जो कि लघुवलयक संघ से सम्बन्धित है। वे नली-के भीतर-नली शारीरिक योजना प्रदर्शित करते हैं; वे आन्तरिक खण्डीभवन के साथ बाह्य रूप से खण्डित हैं; और वे प्रायः सभी खण्डों पर स्फोटिकावृन्त होते हैं। वे विश्वव्यापी होते हैं जहां मृदा, जल और तापमान अनुकूल होती हैं।