What exactly is a "spirit"? Is it invisible? Does it have form? Can it shape-shift and assume other forms?
Is Jehovah a 'spirit'? Is a spirit considered a "creature'?
(paraphrased from abu.nb.ca/Courses/NTIntro/LifeJ/ExorcismJesus.htm)
Gen. 6:1-4 tells us that "spirits" are the disembodied offspring of the watchers who continue their corrupting influence on the human race.
Many texts speak of existence in the post diluvian period of evil spirits subordinate to the ruling evil spirit, variously named Satan, Belial (Beliar), Mastema, angel of darkness, spirit of deceit, Melchiresha, and the Devil, Diabolos.
(paraphrased from Demonology of the Dead Sea Scrolls)
Enochic traditions, Tobic, and other mostly Aramaic writing shaped ideas during First and Second centuries BCE. These non-sectarian documents were composed between the 2nd and 4th centuries BCE
'Spirit' (ruah) is never applied in the absolute sense without being qualified or associated with other Beings. In Aramaic texts---only singular and for evil being.
In the Jubilees, 'spirits' are listed numerous times as evil beings; 'spirit' as a designation for a top ranked malevolent force.
Terms--(demon, spirit, watcher, holy one)
Proper names (for fallen angels, giants, single prominent figures)
Different classes of evil beings
Figures designated in accordance with their functions or characteristics
"In Torah, Israel was forbidden from having any connection with those conversant with the spiritual world. (Lev.19:31; 20:6, 27, Deut. 18:10-11)
This presupposes that such spiritual beings exist, but that Israel is to maintain distance from them."
Saul was tormented by spirit from Yahweh. (1 Samuel 16:14-16; 23)