requies

Etymology
From +.

Noun

 * 1) rest, repose
 * Requiem aeternam dōnā eīs, Domine; et lūx perpetua lūceat eīs. (First line of the introit of the Requiem mass)
 * Grant them eternal rest, Lord; and may perpetual light shine on them.
 * 1) a place of rest

Declension
The singular also attests 5th declension forms.