'Unclean' in the Bible

In the synagogue there was a man who had a spirit of an unclean demon, and he cried out with a loud voice,

Amazement came on all, and they spoke together, one with another, saying, "What is this word? For with authority and power he commands the unclean spirits, and they come out!"

as well as those who were troubled by unclean spirits, and they were being healed.

For Jesus was commanding the unclean spirit to come out of the man. For the unclean spirit had often seized the man. He was kept under guard, and bound with chains and fetters. Breaking the bands apart, he was driven by the demon into the desert.

While he was still coming, the demon threw him down and convulsed him violently. But Jesus rebuked the unclean spirit, and healed the boy, and gave him back to his father.

The unclean spirit, when he has gone out of the man, passes through dry places, seeking rest, and finding none, he says, 'I will turn back to my house from which I came out.'