The word rationale appeared in the second half of the 17th century, just in time for the Age of Reason. It is based on the Latin ratio, which means "reason," and rationalis, which means "endowed with reason." At first, rationale meant "an explanation of controlling principles" ("a rationale of religious practices," for example), but soon it began to refer to the underlying reason for something (as in "the rationale for her behavior"). The latter meaning is now the most common use of the term. The English word ratio can also mean "underlying reason" (in fact, it had this meaning before rationale did), but in current use, that word more often refers to the relationship (in number, quantity, or degree) between things.
Examples of rationale in a Sentence
the rationale for starting the school day an hour later is that kids will supposedly get an extra hour of sleep
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'rationale.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.