n.[C]

1. 原子
2. 微小物；微量，一点儿
   He couldn't produce an atom of evidence.

   他一点证据也拿不出。

n.

1. the smallest particle of a chemical element, consisting of a positively charged nucleus (containing protons and typically also neutrons) surrounded by negatively charged electrons.
2. [usu. with neg.] an extremely small amount.