'inappropriately-used' is a compound formed from 'inappropriately' and 'used'. 'Inappropriately' comes from 'inappropriate' (not suitable), and 'used' is the past participle of 'use'.

'Inappropriately' comes from the prefix 'in-' (not) + 'appropriate' (suitable), and 'used' from Old French 'user', from Latin 'uti' (to use). The compound 'inappropriately-used' is a modern English formation.

Initially, it meant 'used in an unsuitable way', and this meaning has remained the same in modern usage.