1660s, "turned to stone," past participle adjective from petrify (v.). Figurative meaning "paralyzed (with fright, etc.)" is from 1720.
1590s, from Middle French pétrifier "to make or become stone" (16c.), from Latin petra "rock, crag" (see petrous) + -ficare, from facere "to make, do" (see factitious). Metaphoric sense of "paralyze with fear or shock" first recorded 1771. Related: Petrified; petrifying.