A couch is a seat or place used for repose and rest. As a verb, to couch means to crouch, lurk, or lie ready, like a beast prepared to spring upon its prey.
The verb is used when sin is pictured as crouching at the door, warning Cain about temptation and a sullen, jealous disposition. Scripture also uses couching for the recumbent lion of Judah, Issachar resting between the sheepfolds, and the deep beneath.
The noun is closely associated with the biblical bed or place of rest. The image of crouching conveys readiness to spring or to remain concealed.