Verses with the word gross in the Old Testament (2 verses):

Isaiah 60:2
For, behold, the darkness shall cover the earth, and gross darkness the people: but the LORD shall arise upon thee, and his glory shall be seen upon thee.

Jeremiah 13:16
Give glory to the LORD your God, before he cause darkness, and before your feet stumble upon the dark mountains, and, while ye look for light, he turn it into the shadow of death, and make it gross darkness.