'adenoiditis' originates from Greek, specifically the word 'adēn,' where 'adēn' meant 'gland.'

'adēn' transformed into the medical term 'adenoid,' and eventually became the modern English word 'adenoiditis' through the addition of the suffix '-itis' indicating inflammation.

Initially, it meant 'inflammation of glandular tissue,' and this meaning has largely remained the same in modern usage.