n. [ Acc. of L. requies rest, the first words of the Mass being “Requiem aeternam dona eis, Domine, ” give eternal rest to them, O lord; pref. re- re + quies quiet. See Quiet, n., and cf. Requin. ] 1. (R.C.Ch.) A mass said or sung for the repose of a departed soul. [ 1913 Webster ]

We should profane the service of the dead
To sing a requiem and such rest to her
As to peace-parted souls. Shak. [ 1913 Webster ]

2. Any grand musical composition, performed in honor of a deceased person. [ 1913 Webster ]

3. Rest; quiet; peace. [ Obs. ] [ 1913 Webster ]

Else had I an eternal requiem kept,
And in the arms of peace forever slept. Sandys. [ 1913 Webster ]