'Unseen' in the Bible

So shall we come upon David in one of the places where he can be found, and we will fall on him as the dew falls [unseen and unheard] on the ground; and of him and of all the men who are with him, not even one will be left.

“Oh, that You would hide me in Sheol (the nether world, the place of the dead),That You would conceal me until Your wrath is past,That You would set a definite time and then remember me [and in Your lovingkindness imprint me on your heart]!

“But if I look to Sheol (the nether world, the place of the dead) as my home,If I make my bed in the darkness,

“Will my hope go down with me to Sheol (the nether world, the place of the dead)?Shall we go down together in the dust?”

“They fully enjoy their days in prosperity,And so go down to Sheol (the nether world, the place of the dead) in a [peaceful] moment.

For it is kept secret from the eyes of all living, unseen by the birds of the air.

His flesh wastes away to nothing,and his unseen bones stick out.

So that in secret they may let loose their arrows at the upright, suddenly and unseen.

Your way went through the seaand Your path through the great waters,but Your footprints were unseen.

My frame was not unseen by you when I was made secretly, and strangely formed in the lowest parts of the earth.

Therefore Sheol (the realm of the dead) has increased its appetite and opened its mouth beyond measure;And Jerusalem’s splendor, her multitude, her [boisterous] uproar and her [drunken] revelers descend into it.