Late Middle English; earliest use found in The Midland Prose Psalter. From un- + perfect + -ness, originally after post-classical Latin imperfectum and imperfectioimperfection.
Definition of unperfectness in US English:
unperfectness
noun(ˌ)ʌnˈpəːfɪk(t)nɪs
rare
Imperfection.
Origin
Late Middle English; earliest use found in The Midland Prose Psalter. From un- + perfect + -ness, originally after post-classical Latin imperfectum and imperfectio imperfection.