/ ˈaʊtə(r); NAmE / adjective [ only before noun ]
1.
on the outside of sth
SYN external :
the outer layers of the skin
2.
furthest from the inside or centre of sth :
I walked along the outer edge of the track.
the outer suburbs of the city
Outer London / Mongolia
( figurative )
to explore the outer (= most extreme) limits of human experience
OPP inner
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WORD ORIGIN
late Middle English : from out + -er , replacing earlier utter in its obsolete sense outer .