Lewis & Short

introrsum and introrsus (access. form INTROSVS, Inscr. Orell. 4034; v. also introversus), adv. [contr. from intro versum].

  1. I. Form introrsum.
    1. A. Towards the inside, inwards, into: hostem introrsum in media castra accipiunt, Liv. 10, 33.
    2. B. Inwardly, within, on the inside: sed videt hunc omnis domus Introrsum turpem, Hor. Ep. 1, 16, 45; id. S. 2, 1, 64.
  2. II. Form introrsus.
    1. A. Inwards, in, into: ut non facile Introrsus perspici posset, Caes. B. G. 2, 18: reducere aliquid, id. ib. 7, 22: pergit, Tac. A. 2, 25.
    2. B. Inwardly, within: foris nitent, introrsus misera sunt, Sen. Vit. Beat. 2, 4; Liv. 25, 21: lacrimae obortae, Ov. M. 13, 539.