Hallucinate means to see or hear things that aren't really there. This can happen when someone takes certain medicines, has a mental health condition, or experiences extreme stress.
When people talk about hallucinating, they usually mean that their brain is playing tricks on them and creating fake images or sounds that seem real at the time. For example, if someone who's never seen a ghost before sees one in their room, they might say they're hallucinating - it's like their brain made up an image that isn't actually there. Hallucination can also be used to describe a person who hears voices or sees things that don't exist when they're not on any medication.
To seem to perceive things (with one or more of one's senses) which are not really present; to have visions; to experience a hallucination.
