the.com/hallucinogen

means A substance that distorts perception, triggering sensory experiences — visual, auditory, or otherwise — that aren't actually there.

from Built from Latin 'alucinari' (to wander in the mind, to dream), plus the suffix '-gen' (producer of, from Greek 'genes'). The Latin root itself is a bit murky — some trace it further back to Greek 'alyein,' meaning to be distraught or wander in mind. The word 'hallucination' existed in English for centuries before chemists bolted on '-gen' in the 20th century to name the substances that manufacture the wandering mind on demand.