'much-discussed' originates from two elements: 'much' (Old English 'micel'), where 'micel' meant 'great' or 'many', and 'discussed' from Latin 'discutere' via past participle forms (see below), where 'discutere' meant 'to shake apart, examine'.

'much' developed from Old English 'micel' into Modern English 'much'; 'discutere' in Latin gave rise to Late Latin/Old French forms (e.g. Old French 'discuter'), which entered Middle English as 'discuss' and produced the past participle 'discussed'; the compound 'much-discussed' is a Modern English compound combining 'much' + past participle 'discussed'.

Originally the Latin root conveyed a sense of 'shaking apart' or 'examining closely'; over time 'discuss' shifted toward 'talking about or debating', so 'much-discussed' now means 'widely talked about' rather than a literal 'thoroughly examined by shaking apart'.