Lewis & Short

scālāris, e, adj. [scalae], of or belonging to a flight of steps or a ladder: forma, Vitr. 5, 6 fin.; STRVCTIO, Inscr. Orell. 4570.
As subst.: scālārĭa, ĭum, n., a flight of stairs or steps, a staircase, Vitr. 5, 6, 3; also in the sing.: SCALARE, is, Inscr. Orell. 4750.