A sugar contained in milk, white crystalline powder of sweetish taste C₁₂H₂₂O₁₁ obtained from whey and used in pharmacy and infant foods, also called milk sugar.

【化】乳糖，为白色结晶粉状、味甜，取自乳浆，可供药用或作婴儿食品。化学式为 C₁₂H₂₂O₁₁。