ex·ter·nal / ikˈstərnl/ • adj. 1. belonging to or forming the outer surface or structure of something: the external walls. ∎  relating to or denoting a medicine or similar substance for use on the outside of the body: for external application only.2. coming or derived from a source outside the subject affected: for many people the church was a symbol of external authority. ∎  coming from or relating to a foreign country or an outside institution: responsibility for defense and external affairs. ∎  existing outside the mind: the child learns to form conceptions of the external world. ∎  Comput. (of hardware) not contained in the main computer; peripheral. ∎  Comput. (of storage) using a disk or tape drive rather than the main memory.• n. (externals) the outward features of something. ∎  features which are only superficial; inessentials.DERIVATIVES: ex·ter·nal·ly adv.

external exterior. XV. f. L. externus, f. exterus that is outside (cf. EXTERIOR); see -AL1.