hallucination

Universal Words noun 1 [C,U] the fact of seeming to see or hear sb/sth that is not really there, especially because of illness or drugs: to suffer from / have hallucinations * High temperatures can cause hallucination. 2 [C] something that is seen or heard when it is not really there: Was the figure real or just a hallucination? HELPNOTE Some people use an instead of a before hallucination and then usually do not pronounce the 'h'. This now sounds old-fashioned.