Lewis & Short

ū̆trŭbi (ū̆trŏbi and ū̆trĭbi), adv. [uter-ubi], at which of two places, on which of the two sides, where (when two are spoken of; ante- and post-class.): utrubi cenaturi estis? hiccine an in triclinio? Naev. ap. Charis. p. 198 P.: St. Utrubi accumbo? Sa. Utrubi tu vis. St. Cum ambobus volo, Plaut. Stich. 5, 5, 9; cf. id. ib. 5, 4, 14: de frumento utrobi bona, utrobi mala gratia capiatur, Cato ap. Charis. p. 198 P.: utrubi hic homo fuit, Edict. Praet. in Dig. 43, 31 pr. (De utrubi); cf. Gai Inst. 4, § 148 sq.; 4, § 151; Aus. Idyll. 11, 63.