Final answer:
A hallucination is a false, imaginary sensory perception without an external stimulus. It is different from a delusion, which is a false belief, and can be caused by various factors like substance use or brain malfunctions.
Step-by-step explanation:
The term for a false, imaginary sensory perception that occurs in the absence of an external stimulus is hallucination. It can happen due to various factors such as the influence of mind-altering substances, brain malfunctions like chemical imbalances, and can even be a symptom of mental health issues. Hallucinations can affect any of the senses - visual, auditory, olfactory, gustatory, or tactile. Unlike delusions, which are false beliefs, hallucinations are false perceptions. People experiencing hallucinations may see things that aren't there, hear voices, or feel sensations with no physical cause. Understanding hallucinations is important for diagnosing and treating mental health conditions.