Early 19th century; earliest use found in Edward Pusey (1800–1882), Church of England clergyman and theologian. From unpractical + -ness, after practicalness.
Definition of unpracticalness in US English:
unpracticalness
noun(ˌ)ʌnˈpraktɪklnəs
rare
Impracticality.
Origin
Early 19th century; earliest use found in Edward Pusey (1800–1882), Church of England clergyman and theologian. From unpractical + -ness, after practicalness.