Sessor, ris, f. g. Aliud verb. Hor. One that sitteth: a sitter.
Lewis and Short: Latin dictionary
sessor, ōris, m. [sedeo], one who sits in a place, a sitter (not ante-Aug. and very rare). I. In gen., a sitter in the theatre, Hor. Ep. 2, 2, 130.—2.A sitter upon a horse, a horseman, rider, Sen. Const. 12 fin.; Suet. Caes. 61; Veg. 2, 28, 34.— II. In partic., one who tarries or dwells in a place, an inhabitant, resident: sessores veteres urbis, Nep. Cim. 2, 5.