n.

1. 【哲】单子
2. 【生】单细胞生物
3. 【化】一价物
4. 【物】单轴

n.

1. technical a single unit; the number one.
2. Philosophy  (in the philosophy of Leibniz) an indivisible and hence ultimately simple entity, e.g. an atom or a person.
3. Biology,  dated a single-celled organism or a single cell.