Couch or Sofa

A couch, derived from the French coucher (to sleep) was originally a long upholstered seat with a back but no sides on which to recline. The name is therefore correctly used when referring to a ‘psychiatrist’s couch’ as popularised by Sigmund Freud, but inaccurately used in expressions such as ‘couch potato’ and ‘spend the night on the couch’ where the furniture in question is generally taken to be a sofa. Researched this from Sofa Beds Sale where they discuss sofas in great detail.