幻覚

1. Origins, structure, and basic meaning

• Structure: 幻覚(げんかく) means a sensory experience, such as seeing or hearing something, without a corresponding external stimulus.
• Basic usage: It appears in descriptions of experienced sensations, such as seeing insects that are not actually there.

2. Common pitfalls and similar expressions

• Not limited to vision
  • 幻覚を見る describes seeing something that is not there. 幻覚 covers senses beyond vision, including hearing; an auditory hallucination is called 幻聴.