adjective · having a sharp, biting taste like lemon or vinegar

这个葡萄太酸了。

noun · a chemical substance that neutralizes alkalis

这种酸的浓度很高。

adjective, punctuation · aching or feeling stiff, especially in the muscles

走了一整天路，腿都酸了。

verb · to erode or wear away a material by chemical action, specifically by acid.

这种液体能把铁架子酸坏。

adjective · feeling sick at heart, distressed, or sorrowful

听了他的不幸遭遇，我心里感到很酸。

adjective · being impractical, bookish, or prone to making sarcastic remarks

那个穷书生说话总爱带着一股酸气。