Interestingly, it’s sort of a “catholic only” word, but also has to do with defining a state of sleep.
I've heard of that...
Psalm 13:3
Look on me and answer, Lord my God. Give light to my eyes, or I will sleep in death,
Psalm 90:5
Yet you sweep people away in the sleep of death— they are like the new grass of the morning:
Daniel 12:2
Multitudes who sleep in the dust of the earth will awake: some to everlasting life, others to shame and everlasting contempt.
John 11:12-13
His disciples replied, “Lord, if he sleeps, he will get better.”
Jesus had been speaking of his death, but his disciples thought he meant natural sleep.
1 Corinthians 15:51-52
Listen, I tell you a mystery:
We will not all sleep, but we will all be changed—in a flash, in the twinkling of an eye, at the last trumpet.
For the trumpet will sound, the dead will be raised imperishable, and we will be changed.
Ephesians 5:14
This is why it is said: “Wake up, sleeper, rise from the dead, and Christ will shine on you.”
1 Thessalonians 4:13
Brothers and sisters, we do not want you to be uninformed about those who sleep in death, so that you do not grieve like the rest of mankind, who have no hope.