a.

1. 不讲理的，非理智的
   We think he is being unreasonable.

   我们觉得他不讲理。

2. 不合理的；超出情理的；过分的
   The request didn't seem unreasonable.

   这一请求看来并不过分。

adj.

1. not guided by or based on good sense.
2. beyond the limits of acceptability.