'Spirits' in the Bible

When evening came, they brought to him many possessed with demons. He cast out the spirits with a word, and healed all who were sick;

He called to himself his twelve disciples, and gave them authority over unclean spirits, to cast them out, and to heal every disease and every sickness.

Then he goes, and takes with himself seven other spirits more evil than he is, and they enter in and dwell there. The last state of that man becomes worse than the first. Even so will it be also to this evil generation."