Rōōst1, n.
n. [A-S. hrōst, D. roest, roost, roosten, to roost.] 1. The pole or other support on which birds rest at night; a perch.
He clasped his wings upon his roost. Dryden.
Sense 2. A collection of fowls roosting together.
At roost, in a state of rest and sleep.