乳酸

1. Origins, structure, and basic meaning

• Structure: 乳酸(にゅうさん) is the name of lactic acid. 酸 identifies it as an acid.
• Basic usage: It is used when measuring the amount of lactic acid in an experiment or discussing its structure in class.

2. Common pitfalls and similar expressions

• A different substance from 乳糖
  • 乳糖(にゅうとう) is lactose, a sugar. Despite sharing their first character, 乳酸 and 乳糖 name an acid and a sugar respectively.