Mid 18th century (in an earlier sense). From classical Latin repugnātōrius of defence or resistance, defensive from repugnāt-, past participial stem of repugnāre + -ōrius.
Definition of repugnatory in US English:
repugnatory
adjectiverɪˈpʌɡnət(ə)ri
Zoology= repugnatorial.
Origin
Mid 18th century (in an earlier sense). From classical Latin repugnātōrius of defence or resistance, defensive from repugnāt-, past participial stem of repugnāre + -ōrius.