Bhuta

the term bhuta (or bhut - from bhu - to become) has a variety of meanings, depending on context. It can be taken to refer to a ghost - particularly one which attacks or possesses; or a demon (in the Greek, rather than the Judeo-Christian sense of the word). In tantra practice, bhuta suddhi is a ritual of bodily purification in which the sadhaka 'destroys' the gross elements in the body and then creates a 'divine' body by means of visualisation, mantra, and nyasa. Suddhi is derived from sudh - 'to purify'.

In the context of Bhuta Suddhi, the Bhutas are the Five Elements: Earth, Water, Fire, Wind and Space (ether).

Bhutas are also part of Siva's attendant horde of restless spirits - the ganas.

Bhutesvara - "Lord of Ghosts" is an epithet of Lord Siva.

References:
The Purification of the Body Gavin Flood, in Tantra in Practice, David Gordon White (ed.), Princeton University Press, 2000.
Lakshmi Tantra Shakti L. Gupta (transl.) Motilal
Ghosts: Life and death in North India Freed & Freed, AMNH Papers No.72