a.

1. 酸的，有酸味的
   Lemons have an acid taste.

   柠檬有酸味。

2. 【化】酸性的
3. 尖酸刻薄的
   John has an acid tongue.

   约翰说话尖刻。

4. 敏锐的

n.

1. 【化】酸[C][U]
   Some acids burn holes in wood and cloth.

   有些酸类会在木和布上烧出洞来。

2. 有酸味的东西[U]
3. 尖刻，讥刺[U]
4. 【俚】迷幻药[U]

n.

1. a substance (typically, a corrosive or sour-tasting liquid) with particular chemical properties including turning litmus red, neutralizing alkalis, and dissolving some metals.
2. Chemistry  any molecule able to donate a proton or accept electrons in reactions.
3. informal the drug LSD.

adj.

1. containing or having the properties of an acid; having a pH of less than 7.
2. sharp-tasting or sour.
3. (of remarks) bitter or cutting.
4. Geology  & Metallurgy  rich in silica.