roost1
n.
a place where birds regularly settle to rest at night, or where bats congregate to rest in the day.
v.
(of a bird or bat) settle or congregate for rest.
Etymology
OE hrōst; of unknown ultimate origin.
roost2
n.
(in the Orkneys and Shetlands) a tidal race.
Etymology
C17: from ON rǫst.