I. pre ‧ fix 1 /ˈpriːfɪks/ BrE AmE noun [countable]
[ Date: 1600-1700 ; Language: Modern Latin ; Origin: praefixum , from Latin praefigere 'to fasten before' ]
1 . technical a group of letters that is added to the beginning of a word to change its meaning and make a new word, such as ‘un’ in ‘untie’ or ‘mis’ in ‘misunderstand’ ⇨ affix , suffix
2 . a number or letter that comes before other numbers or letters, especially a group of numbers that comes before a telephone number when you are calling someone in a different area
3 . old-fashioned a title such as ‘Ms’ or ‘Dr’ used before someone’s name SYN title
II. prefix 2 BrE AmE verb [transitive]
[ Date: 1400-1500 ; Language: Old French ; Origin: prefixer , from fixer 'to fix' ]
1 . to add a prefix to a word, name, or set of numbers
2 . formal to say something before the main part of what you have to say