'inadvertently-assisted' originates from the adverb 'inadvertently' and the past-participle form 'assisted'. The adverb 'inadvertently' ultimately derives from Latin elements 'in-' (not) + 'advertere' (to turn toward), while 'assist' originates from Latin 'assistere' (to stand near), via Old French.

'inadvertently-assisted' formed in modern English by combining the adverb 'inadvertently' (from Middle English/Old French forms of 'inadvertent', originally from Latin 'in-' + 'advertere') with the past participle 'assisted' (from Old French 'assister', from Latin 'assistere').

Originally, Latin 'assistere' meant 'to stand near' and 'inadvertent' meant 'not turned toward (unintentional)'; over time 'assist' shifted to mean 'to help', and the compound came to mean 'help given unintentionally'.