perrŏgātĭo, ōnis, f. [perrogo],
I a decree , Inscr. Maff. Mus. Ver. 288, 4.—
II The passage of a law : perrogationem legis Maniliae flagitasti, Cic. Mur. 23, 47.
perrogātiō ōnis, f perrogo, the enactment of a law : legis Maniliae. ...
An Elementary Latin Dictionary