late O.E. hrost "wooden framework of a roof, perch," from a Gmc. source, related to O.S. hrost, M.Du., Flem., Du. roest, roost "framework of a roof," O.N. hrot, Goth. hrot "roof." Exact relationship and ulterior connections unknown. The verb is from 1530. To rule the roost is recorded from 1769.