prefix

v. place before or in front of; add a prefix, add a word or word stem to the beginning of a word; set or arrange in advance

n. word or word stem used at the beginning of a word; title (as "Mr." or "The Honorable" before a person's name); word part added to the beginning of a word to change its meaning (Grammar); dialing code, area code (for telephones)

A prefix is the initial portion of some object or term (typically in text or speech) with a distinct and he base semantics for a word.Numerical prefix, used for magnitudes of SI units, like 'kilo' and 'milli' in 'kilometre' and 'milligram'. See also SI prefix.Polish notation, a method of mathematical expression, also known as prefix notationTelephone prefix, the first set of digits in a telephone number not a country code or area codeITU prefix, a call sign for radio and television stationsPrefix (computer science), of a stringPrefix code 
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Noun
1. an affix that added in front of the word
(hypernym) affix
(hyponym) alpha privative
Verb
1. attach a prefix to; "prefixed words"
(antonym) suffix
(hypernym) affix
(derivation) prefixation

adj. prefixed, attached to the beginning of a word, predetermined

(v. t.)
To set or appoint beforehand; to settle or establish antecedently.
  

(v. t.)
To put or fix before, or at the beginning of, another thing; as, to prefix a syllable to a word, or a condition to an agreement.
  

(n.)
That which is prefixed; esp., one or more letters or syllables combined or united with the beginning of a word to modify its signification; as, pre- in prefix, con- in conjure.