Definition of "prefix"

Something placed before another

1. (grammar, linguistic morphology) A morpheme added to the beginning of a word to modify its meaning, for example as, pre- in prefix, con- in conjure, re- in reheat, etc.

2. (telecommunications) A set of digits placed before a telephone number, to indicate where the number is based, what type of phone number it is (landline, mobile, toll-free, premium rate etc.)  examples

3. A title added to a person's name, such as Mr. or Dr.  examples

4. (computing) An initial segment of a string of characters.  examples

(transitive) To determine beforehand; to set in advance.  quotations  examples

(transitive) To put or fix before, or at the beginning of something; to place at the start.  examples