a.

1. 理性的，有理性的；明事理的
   Panic destroys rational thought.

   驚慌摧毀理性思考。

2. 基於理性的，合理的
   That's a rational decision.

   那是個合理的決定。

3. 【數】有理的

n.[C]

1. 合理的事物
2. 【數】有理數

adj.

1. based on or in accordance with reason or logic.
2. able to think sensibly or logically.
3. having the capacity to reason.
4. Mathematics  (of a number, quantity, or expression) expressible, or containing quantities which are expressible, as a ratio of whole numbers.