Definition of rationalness in English:

rationalness

noun

  • The quality or state of being rational.

Pronunciation

rationalness

/ˈraʃ(ə)n(ə)lnəs/ /ˈraʃən(ə)lnəs/

Origin

Mid 17th century; earliest use found in Henry Hammond (1605–1660), Church of England clergyman and theologian. From rational + -ness.