'fetid' originates from Latin, specifically the word 'fetidus' (also attested as 'foetidus'), where the root 'foet-' meant 'to stink' or 'foul smell'.

'fetid' changed from the Latin word 'fetidus'/'foetidus' and was adopted into English (via late Latin and occasional Old French influence) to become the modern English word 'fetid'.

Initially it meant 'having a strong or offensive smell', and over time it has retained this primary meaning of 'stinking' or 'foul-smelling'.