'doubtfully-built' originates from the combination of 'doubtful' and 'built', where 'doubtful' comes from the Old French 'doute', meaning 'fear' or 'uncertainty', and 'built' is the past participle of 'build', from Old English 'byldan'.

'doubtful' evolved from the Old French 'doute' and Middle English 'douteful', while 'built' comes from the Old English 'byldan', eventually forming the modern English term 'doubtfully-built'.

Initially, 'doubtful' meant 'full of doubt or fear', and 'built' referred to 'constructed'. Together, they evolved to describe something constructed with questionable quality.