v. i. [ L. hallucinatus, alucinatus, p. p. of hallucinari, alucinari, to wander in mind, talk idly, dream. ] 1. To wander; to go astray; to err; to blunder; -- used of mental processes. [ R. ] Byron. [ 1913 Webster ]

2. Specifically: To perceive a non-existent object or phenomenon; to believe that one is experiencing something which in reality does not exist; to experience a hallucination{ 2 }. [ PJC ]

v. t. To experience (something nonexistent) as an hallucination{ 2 }. [ PJC ]

adj. Experiencing hallucinations.
Syn. -- delirious. [ WordNet 1.5 +PJC ]

n. [ L. hallucinatio: cf. F. hallucination. ] 1. The act of hallucinating; a wandering of the mind; error; mistake; a blunder. [ 1913 Webster ]

This must have been the hallucination of the transcriber. Addison. [ 1913 Webster ]

2. (Med.) The perception of objects which have no reality, or of sensations which have no corresponding external cause, arising from disorder of the nervous system, as in delirium tremens; delusion. [ 1913 Webster ]

Hallucinations are always evidence of cerebral derangement and are common phenomena of insanity. W. A. Hammond. [ 1913 Webster ]

n. [ L. ] One whose judgment and acts are affected by hallucinations; one who errs on account of his hallucinations. N. Brit. Rev. [ 1913 Webster ]

a. Partaking of, having the character of, or tending to produce, hallucinations; as, hallucinatory visions. [ 1913 Webster +PJC ]