A triclinium (pl.: triclinia) is a formal dining room in a Roman building. The word is adopted from the Greek triklinion (τρικλίνιον)—from tri- (τρι-), "three", and klinē (κλίνη), a sort of couch, or rather chaise longue. Each couch was sized to accommodate a diner who reclined on their left side on cushions while some household slaves served multiple courses brought from the culina, or kitchen, and others entertained guests with music, song, or dance.
The triclinium was characterized by three lecti (singular lectus: bed or couch), called triclinares ("of the triclinium"), on three sides of a low square table, whose surfaces sloped away from the table at about 10 degrees. Diners would recline on these surfaces in a semi-recumbent position. The fourth side of the table was left free, presumably to allow service to the table. Usually, the open side faced the entrance of the room. In Roman-era dwellings, particularly wealthy ones, triclinia were common and the hosts and guests would recline on pillows while feasting.