rational

Compared meaning: sensible, based on logic or fairness (adjective).

比较义项：合理的、理性的（形容词）。

• reasonable

  Describes something fair, sensible or moderate that people find acceptable — often a price, request, offer or behavior — judged by common sense, not necessarily by logical reasoning.

  指公平、明理或适度、让人能够接受的事物——常用于价格、要求、提议或行为——凭常识判断，而不一定涉及逻辑推理。

  The landlord agreed to a reasonable rent that both sides were happy with.

  房东同意了一个双方都满意的合理租金。

• rational 本词

  Describes thinking, decisions or people based on logic and clear reasoning rather than emotion; used for the reasoning process itself, less often for prices or requests.

  指思维、决定或人是基于逻辑和清晰推理，而非情绪；用于描述推理过程本身，较少用于价格或要求。

  She stayed calm and made a rational choice instead of panicking.

  她保持冷静，做出了理性的选择，而不是惊慌失措。

Reasonable and rational both mean sensible, but focus on different things. Reasonable describes something fair or moderate that people accept, like a price, judged by common sense. Rational describes thinking or people based on clear logic, not emotion. This excludes reasonable meaning a moderate amount.

这两个词都可译作“合理的”，但侧重不同：reasonable 强调结果公平、适度，让人容易接受，常用于价格、要求、行为等；rational 强调思维过程基于逻辑推理而非情绪，常用于决定、想法、人本身。这里不比较 reasonable 的其他义项，如“数量适中的”。