priorsum

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.

prĭorsum and prĭorsus, adv. [prisversus],

forwards (post-class.): corpus aut accedit priorsum, aut retrorsum recedit (al. prorsum), Macr. S. 7, 9: pergere, id. ib. 7, 13: movetur corpus priorsus ac retrorsus, Claud. Mam. Stat. Anim. 1, 18.