Source:
http://en.wikipedia.org/wiki/Messiah
, Standard Mašíaḥ Tiberian Māšîªḥ; Aramaic: משיחא, Aramaic/Syriac: ܡܫܺܝܚܳܐ, Məšîḥā; Arabic: المسيح, al-Masīḥ) Literally, Messiah means "The Anointed (One)", typically someone anointed with holy anointing oil. Figuratively, anointing is done to signify being chosen for a task; so, Messiah means "The Chosen (One)", particularly someone divinely chosen.
In Jewish messianic tradition and eschatology, Messiah refers to a future Jewish King from the Davidic line, who will be and rule the Jewish people during the Messianic Age. In Standard Hebrew, The Messiah is often referred to as מלך המשיח, Méleḫ ha-Mašíaḥ (in the Tiberian vocalization pronounced Méleḵ hamMāšîªḥ), literally meaning "the Anointed King."
Christians believe that prophecies in the Hebrew Bible refer to a spiritual savior, and consider Jesus to be that Messiah (Christ). In the (Greek) Septuagint version of the Old Testament, khristos was used to translate the Hebrew מָשִׁיַח (Mašíaḥ,) (messiah), meaning "anointed." [1]
In Islam, Jesus (Isa) is also called the Messiah (Masih)[2] but is not considered to be the Son of God.
The Septuagint translation of the Hebrew Bible into Greek translates all thirty-nine instances of the word messiah as Christos. The New Testament records the Greek transliteration Μεσσίας, Messias, twice, in John 1:41 and 4:25.
One anointed with holy oil or one who is chosen (for a task). The definition above also provides the etymology of the word as well.
[Wikipedia isn't the be all and end all of information, but its pretty darn good (and convenient)]
Regards,
netwrkranger