Lewis & Short

collis, is (abl. reg. colle, e. g. Ov. M. 1, 698; 14, 90; 14, 333; 14, 822; 14, 836; Caes. B. G. 1, 24; 2, 18; Sall. J. 52, 3: Aventino, Liv. 1, 3, 9 et saep.; colli, Lucr. 2, 317 and 322; Auct. Aetn. 466; gen. plur. collium, Tac. Agr. 37; Lact. Opif. Dei, 10), m. [cel-, root of ex-cello, celsus; cf. calamus], high ground, a hill (opp. mons and campus), Lucr. 5, 1373; Cic. Verr. 2, 3, 18, § 47; Caes. B. G. 2, 8; 7, 19: altus, Ov. M. 15, 306: aperti, Verg. G. 2, 112: aprici, id. E. 9, 49: celsus, id. A. 8, 604: supini, id. G. 3, 555: inter Palatinum Capitolinumque, Liv. 1, 12, 1; cf. id. 5, 54, 3 sq.: Dianae, i.e. Aventinus, Mart. 12, 18, 3.
Poet., = mons: collis Heliconii cultor, Cat. 61, 1.
And in plur.: colles, for a chain of mountains, Sil. 3, 420.
Hence, Ital. collina; Fr. colline.