A triclinium was a Roman dining couch or dining arrangement set along three sides of a square room, with the fourth side open for food or tables. It was designed for reclining at meals.
Reclining at meals was common in New Testament times, even where English translations say “sat.” In John 2, the ruler or governor of the feast is called the master of the triclinium.
The arrangement was characteristic of Roman dining rooms, including alcoves in larger houses. Earlier Old Testament passages describe people sitting at meals, while reclining was viewed as a foreign luxury adopted by later aristocracy before becoming common in New Testament times.