rationale
/ˌræʃəˈnɑːlɪ/noun
- a set of reasons or a logical basis for a course of action or a particular belief全部理由, 根本原因, 逻辑依据：
he explained the rationale behind the change.
他把变化的根本原因做了解释。
词源
mid 17th cent.: modern Latin, neuter (used as a noun) of Latin rationalis'endowed with reason' （see RATIONAL）.