Lewis & Short

trĭpartītus or -pertītus, a, um, Part. [ter-partior], divided or divisible into three parts, threefold, tripartite (rare, but good prose): ea causa tripertita erit in accusatione, Cic. Verr. 2, 3, 5, § 12: qui tripertitas orbis terrarum oras atque regiones notavit, id. Sest. 61, 129: tripartita ab iis inducitur ratio bonorum, id. Ac. 1, 5, 21: divisio tripartita (al. tripertita), id. Off. 3, 2, 9: exercitus, Tac. A. 2, 74: jus privatum, quod tripartitum est, Just. Inst. 1, 1, 4.
Substt

    1. 1. Trĭpertīta, ōrum, n., the title of a treatise by Sex. Aelius: exstat illius (Sex. Aelii) liber, qui inscribitur Tripertita, Dig. 1, 2, 2, § 38.
    2. 2. Trĭpertīta, ae, f., the title of a comedy by Novius, Non. 218, 15.
      Adv.: trĭpartītō (-pertītō), in or into three parts: qui bona dividit tripertito, Cic. Tusc. 5, 13, 40: tripartito divisus equitatus, Caes. B. G. 7, 67; Hirt. B. G. 8, 33: Caesar partitis copiis … adit tripartito, Caes. B. G. 6, 6: aggreditur urbem, Liv. 21, 7.