'faultily-installed' originates from the combination of 'faultily,' an adverb form of 'faulty,' and 'installed,' the past participle of 'install.'

'Faultily' comes from the Middle English 'faute,' meaning 'defect,' and 'installed' from the Latin 'installare,' meaning 'to set up.'

Initially, 'faultily' meant 'in a defective manner,' and 'installed' meant 'set up or established.' The combined term retains these meanings.