external

adjective

• 1belonging 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

• 2coming or derived from a source outside the subject affected:for many the Church was a symbol of external authority the child learns to form conceptions of the external world
• coming from or relating to a country or institution other than the main subject:a department of external affairs
• for or concerning students registered with and taking the examinations of a university but not resident there:external degrees

• 3 Computing (of hardware) not contained in the main computer; peripheral.
• (of storage) using a disk or tape drive rather than the main memory.

noun

• the outward features of something:the place has all the appropriate externals, such as chimneys choked with ivy
• inessential or superficial features: photographs can only show externals