suf ‧ fix /ˈsʌfɪks/ BrE AmE noun [countable]
[ Date: 1600-1700 ; Language: Modern Latin ; Origin: suffixum , from Latin suffigere 'to fasten beneath' , from sub- ( ⇨ ↑ sub- ) + figere 'to fasten' ]
a letter or letters added to the end of a word to form a new word, such as ‘ness’ in ‘kindness’ or ‘ly’ in ‘suddenly’ ⇨ affix , prefix