Not performable; especially impossible to perform or accomplish successfully.
Origin
Late 16th century; earliest use found in Abraham Fleming (c1552–1607), author, literary editor, and Church of England clergyman. From un- + performable.
Definition of unperformable in US English:
unperformable
adjective(ˌ)ʌnpəˈfɔːməbl
Not performable; especially impossible to perform or accomplish successfully.
Origin
Late 16th century; earliest use found in Abraham Fleming (c1552–1607), author, literary editor, and Church of England clergyman. From un- + performable.