Lewis & Short

bĭsellĭum, ii, n. [bis-sella], a richly ornamented seat of honor (so called because there was room for two persons upon it, although only one sat thereon, Varr. L. L. 5, § 128 Müll.). Such a bisellium has been found represented upon a Pompeian tomb with the inscription: C. CALVENTIO. … BISELLII. HONOR. DATVS. EST., Inscr. Orell. 4044; cf. ib. 4046; 4047; 4048.