RATIONALE Meaning of RATIONALE in English [ ˌraʃə'nα:l ]■ noun a set of reasons or a logical basis for a course of action or a belief.OriginC17: mod. L., neut. (used asnoun) of L. rationalis (see rational ). Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004