Lewis & Short

vătĭus, a, um, adj., bent outwards: (canes) sint cruribus rectis et potius varis quam vatiis, Varr. R. R. 2, 9, 4; hence, of persons with legs bent out wards, bowlegged: quaesitum est, an balbus et blaesuset varus et vatius sanus sit, Dig. 21, 1, 10 fin.; Mart. 12, 70, 1.
Subst.: vătĭa, ae, m., a bowlegged man: imitari vatias, Varr. L. L. 9, § 10 Müll.; cf. Plin. 11, 45, 105, § 204.