Late 18th century; earliest use found in Hugh Brackenridge (1748–1816), writer and judge. From perorate + -ory. Compare post-classical Latin peroratorius thoroughly oratorical.
Definition of peroratory in US English:
peroratory
adjectivepɛˈrɒrət(ə)ri
= perorational.
Origin
Late 18th century; earliest use found in Hugh Brackenridge (1748–1816), writer and judge. From perorate + -ory. Compare post-classical Latin peroratorius thoroughly oratorical.