Main Entry: ra·tio·nal

Pronunciation: \ˈrash-nəl, -ən-^əl\

Function: adjective

1 a : having reason or understanding b : relating to, based on, or agreeable to reason <a rational explanation> <rational behavior>
2 : using medical treatments based on reason or general principles—used especially of an ancient school of physicians; compare empirical 1a

—ra·tio·nal·ly \-ē\ adverb