1 (used about a person) able to use logical thought rather than emotions to make decisions （指人）理性的，理智的 [OPP] irrational 反义词为irrational

2 based on reason; sensible or logical 基于理性的；合理的: There must be a rational explanation for why he's behaving like this. 他为什么有这样的行为，必然有合理的解释。 ➔rationally adv