胃酸

1. Origins, structure, and basic meaning

• Structure: 胃酸（いさん） refers to the acidic component of the gastric fluid secreted in the stomach.
• Basic usage: Use it when learning about the stomach in science class or asking questions relating to an examination.

2. Common pitfalls and similar expressions

• The same reading with a different meaning
  • 遺産 is also read いさん, but means an inheritance or a legacy.