a.

1. 可理解的
   His reluctance to agree is understandable.

   他不愿同意是可以理解的。

2. 能懂的；可了解的
   They tried to store information in a form which is readily understandable.

   他们试着用一种易懂的方式储存信息。

adj.

1. able to be understood.
2. to be expected; natural, reasonable, or forgivable.