Lewis & Short

călĭgārĭus, a, um, adj. [caliga], of or pertaining to the soldier’s boot: clavus, Plin. 34, 14, 41, § 143.
Hence, with sutor, Inscr. Grut. 649, 1.
As subst.: călĭgārĭus, ii, m., a maker of soldiers’ boots, a shoemaker, Lampr. Alex. Sev. 33; Firm. Matth. 3, 12; Inscr. Spon. Misc. 220.