Mid 18th century; earliest use found in Patrick Murdoch (d. 1774), Church of England clergyman and writer. After German Defensional (noun); compare post-classical Latin defensionalis (in speeches) defensive, capable of defending.
Definition of defensional in US English:
defensional
adjective
rare
Of or relating to defence; defensive.
Origin
Mid 18th century; earliest use found in Patrick Murdoch (d. 1774), Church of England clergyman and writer. After German Defensional (noun); compare post-classical Latin defensionalis (in speeches) defensive, capable of defending.