A sofa is similar to a couch — officially, it needs to seat at least three or more people to qualify as a sofa. If only two people can fit, it's a love seat. And if it's only big enough for you and your pet hedgehog, it's an armchair. Sofas are typically upholstered, with a high back and arms. The word originated from Turkish, from an Arabic root, suffa, "bench of stone or wood."