Webster's Revised Unabridged Dictionary · 1913

Requiem

Requiem (r?"kw?-?m;277) , noun

[Acc. of Latin 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 compare Requin.]

1.
(R.C.Ch.) A mass said or sung for the repose of a departed soul.
Requiem aeternam dona eis, Domine,
We should profane the service of the dead To sing a requiem and such rest to her As to peace-parted souls. — Shakespeare
2.
Any grand musical composition, performed in honor of a deceased person.
3.
Rest; quiet; peace. [Obsolete]
Else had I an eternal requiem kept, And in the arms of peace forever slept. — Sandys