Main Entry: ¹ra·tio·nal

Pronunciation: \ˈrash-nəl, ˈra-shə-n^əl\

Function: adjective

Etymology: Middle English racional, from Anglo-French racionel, from Latin rationalis, from ration-, ratio

Date: 14th century

1 a : having reason or understanding b : relating to, based on, or agreeable to reason : reasonable <a rational explanation> <rational behavior>
2 : involving only multiplication, division, addition, and subtraction and only a finite number of times
3 : relating to, consisting of, or being one or more rational numbers <a rational root of an equation>

— ra·tio·nal·ly adverb

— ra·tio·nal·ness noun