IPA: /ɪkˈstɪəriəli/
KK: /ɪkˈstɪrɪərli/
In a way that relates to the outside or outer surface of something.
The building was beautifully designed, but exteriorly it looked quite plain.
Exteriorly → It is formed from "exterior" (from Latin "exterior" meaning outer or outside) and "-ly" (meaning in a manner of). The word "exteriorly" means in a manner that is related to the outer surface or outside.
Think of 'exterior' meaning outside, and remember that 'exteriorly' describes something done in an outside manner.