Lewis & Short

dorsum, i, n. (masc. dorsus, Plaut. Mil. 2, 4, 44; quoted ap. Non. 203, 6) [cf. Gr. δειρή, δέρη, neck], the back (in class. prose, only of beasts of burden; poet. and later also of men; cf.: tergum, tergus).

  1. I. Prop., Plaut. l. l.; id. Ep. 1, 1, 85; id. Trin. 3, 2, 93; Plin. 11, 37, 86, § 214; Verg. G. 3, 116; Hor. S. 1, 9, 21.
    Prov.: dorsus prurit, i. e. I begin to take, Plaut. Mil. 2, 4, 44.
  2. II. Transf., of things analogous in form or position: jugi, i. e. the ridge, summit of a hill, * Caes. B. G. 7, 44; Liv. 44, 4: montis, id. 1, 3; 41, 18; Tac. A. 4, 47: Apennini, Suet. Caes. 44: praerupti nemoris, Hor. S. 2, 6, 91; cf. nemoris, Verg. G. 3, 436: speluncae, i. e. the rock, id. A. 8, 234; cf. of a cliff, id. ib. 1, 110; 10, 303 Serv.; Plin. Ep. 6, 31, 17; 9, 7, 4: viae, the raised part of it, Stat. S. 4, 3, 44: duplex dentalium, the projecting irons, Verg. G. 1, 172.