Pronunciation: (hu-lOO"su-nā'shun), [key]
1. a sensory experience of something that does not exist outside the mind, caused by various physical and mental disorders, or by reaction to certain toxic substances, and usually manifested as visual or auditory images.
2. the sensation caused by a hallucinatory condition or the object or scene visualized.
3. a false notion, belief, or impression; illusion; delusion.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.