hallucinate

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 ]