a couch extending along three sides of a table, for reclining on at meals.
2.
a dining room, esp. one containing such a couch.
Origin: 1640–50; < L trīclīnium < Gk triklnion, dim. of tríklīnos having three couches (adj.), dining room so furnished (n.), equiv. to tri-tri-+ kln(ē) couch (see clinic) + -ion dim. suffix
tri·clin·i·um (trī-klĭn'ē-əm) n.
pl.tri·clin·i·a (-ē-ə)
A couch facing three sides of a rectangular table, used by the ancient Greeks, Etruscans, and Romans for reclining at meals.
A room containing such a couch or couches; a dining room.
[Latin trīclīnium, from Greek triklīnion, diminutive of triklīnos, room with three couches : tri-, three; see trei- in Indo-European roots + klīnē, couch; see klei- in Indo-European roots.]