'unappetizingly' originates from English, specifically the word 'unappetizing', where 'un-' meant 'not' and 'appetizing' derives from 'appetize' (ultimately from Latin 'appetitus'/'appetere' meaning 'desire' or 'to seek'), with the adverbial suffix '-ly' added to form the adverb.

'unappetizingly' developed by attaching the negative prefix 'un-' to 'appetizing' (from Middle French/Old French roots of Latin 'appetitus'), producing 'unappetizing' in modern English, and then adding the adverbial suffix '-ly' to yield 'unappetizingly'.

Initially, the root 'appetize' meant 'to stimulate the appetite' (from Latin 'appetere'/'appetitus'), and over time 'appetizing' came to mean 'appealing to the appetite'; the prefixed and suffixed form 'unappetizingly' now means 'in a manner that is not appealing to the appetite'.