From Longman Dictionary of Contemporary Englishsofaso‧fa /ˈsəʊfə $ ˈsoʊ-/ ●●● S3 noun [countable] 
DHFa comfortable seat with raised arms and a back, that is wide enough for two or three people to sit on SYN couch, settee British English
DHFa comfortable seat with raised arms and a back, that is wide enough for two or three people to sit on SYN couch, settee British EnglishExamples from the Corpus
sofa• If they sat on a sofa, they sat close together; often they shared an armchair.• He looked very big filling up that little sofa.• She retreated back downstairs, and climbed on to the mildewed sofa, hugging her knees up to her chin.• Then Stan rises from the sofa and goes outside for a cigarette.• On the table in front of the sofa was a vase holding four pink roses, the blooms in various stages of uncurled perfection.• Whitlock smiled at her then looked beyond her at the couple on the sofa.• Instead, I took my shoe off and lay down on the sofa.Origin sofa (1600-1700) Arabic suffah “long seat” 