a.

1. 不确定的；含混的
2. 数量及性质不明的
   An indeterminate number of illegal immigrants have entered our country.

   一群数量不明的非法移民已进入我们国家。

adj.

1. not exactly known, established, or defined.
   ▸Mathematics  (of a quantity) having no definite or definable value.
   ▸Medicine  (of a condition) from which a diagnosis of the underlying cause cannot be made.
2. Botany  (of a shoot) not having all the axes terminating in flower buds and so potentially of indefinite length.