Lewis & Short

compendĭārĭus, a, um, adj. [compendium],

  1. I. short, compendious, only a few times of ways or roads: via ad gloriam proxima et quasi compendiaria, * Cic. Off. 2, 12, 43; cf. Val. Max. 7, 2, ext. 1.
  2. II. Subst.
    1. A. compendĭārĭa, ae, f. (sc. via), a short way or method; fig., Varr. ap. Non. p. 202, 5; Petr. 2, 9; Sen. Ep. 119, 1; cf. id. ib. 27, 5: breviores etiamnum quaedam picturae compendiariae, Plin. 35, 10, 36, § 110.
    2. B. compendĭārĭum, ii, n. (sc. iter), the same, Sen. Ep. 73, 11.