Lewis & Short

auctrix, īcis, f. [auctor].

  1. I. She that originates a thing, an author (very rare, and post-class. for auctor, q. v. fin.): materia auctrix universitatis, Tert. adv. Herm. 5: anima auctrix operum carnis, id. adv. Marc. 5, 10: comoediae scelerum et libidinum auctrices, id. Spect. 18.
  2. II. A female seller or surety (very rare, and post-class.), Cod. Diocl. et Max. 8, 45, 16; Tert. Anim. 57.