[no obj.]experience a seemingly real perception of something not actually present, typically as a result of a mental disorder or of taking drugs (尤指由于精神错乱或吸毒而)产生幻觉 they thought he was seeing things, hallucinating. 他们认为他在幻觉中看见了什么。 ■[with obj.]experience a hallucination of (something) 出现(或产生)…的幻觉
mid 17th cent. (in the sense 'be deceived, have illusions'): from Latin hallucinat- 'gone astray in thought', from the verb hallucinari, from Greek alussein 'be uneasy or distraught'