early 15c., "overt;" by 1590s as "situated or lying outside," from Latin externus "outside, outward" (from exterus; see exterior) + -al (1). This version won out over exterial. Related: Externally.
external commerce
external pressures
the external auditory canal
external composure
he enjoyed the solemn externals of religion
exterior
exterminate
extermination
exterminator
extern
external
externality
externalization
externalize
extinct
extinction