TRICLINIUM, in Roman antiquities, a set of three couches (lecti) arranged round a four-sided dining table, one side of which was left open to provide free access for the attendant slaves. These couches were distinguished as the highest (A, lectus summus), the middle (B, lectus medius) and the lowest (C, lectus imus) ; the guests who reclined on B had A on their left and C on their right. Each couch was usually occupied by three persons, whose left arm rested on a cushion, the right hand being thus disengaged for purposes of eating. The nine places were allotted in accordance with strict etiquette. A and B were reserved for the guests (B for the most distinguished), C for the host and his family. In A and C the chief place was i; in B it was 3, which 1zz | 1 1zz 2 i I summus imus 3 2 medius medius 2 3 imus summus l was consequently the place of honour at the banquet. It was called locus consularis (wcm/cos) , probably as being next to the host. Another explanation is that, since it was on the open and unsupported side of the couch, it was chosen in order that, if a consul happened to be present among the guests, he might be able to receive communications, sign documents or transact business with the least inconvenience. It the locus classicus in Horace (Satires, ii. 8, 20-23), which describes the banquet given by Nasidienus in honour of Maecenas, the host appears to have resigned his place to Nomentanus, as being more capable of entertaining the guest of the evening. In later republican times, after the introduction of round tables of citrus wood, the three couches were replaced by one of crescent shape (called sigma from the form C of the Greek letter; also stibadium and accubitum), which as a rule was only intended to hold five persons. The two corner seats (cornua) were the places of honour, that on the right being considered superior. The remaining seats were reckoned from left to right, so that the least important seat was on the left side of the most important. The use of the sigma continued till the middle ages. The dining-room itself was also called triclinium, and in the houses of wealthy Romans there were several triclinia suited to the different seasons of the year.
See Marquardt, Das Prwatleben der Rdmer (1886), p. 302.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)