Peace Light,
Read this again:
Although, every prophet of God is an ANOINTED one of God - a Messiah, the title "Masih" or "Messiah" or its translation "CHRIST" is exclusively reserved for Jesus, the son of Mary, in both Islam and in Christianity. This is not unusual in religion. There are certain other honorific title which may be applied to more than one prophet, yet being made exclusive to one by usage: like "Rasul-lullah", meaning Messenger of God, which title is applied to both Moses (19:51) and Jesus (61:6) in the Holy Quran. Yet "Rasul-lullah" has become synonymous only with the Prophet of Islam among Muslims.
Every prophet is indeed a FRIEND OF GOD, but its Arabic equivalent "Kha- lil-lullah" is exclusively associated with Father Abraham. This does not mean that the others are not God's friends. "Kalimul-lah" (One who spoke with God) is never used for anyone other than Moses, yet we believe that God spoke with all His Messengers, including Jesus and Muhummed (May the Peace and Blessings of God be upon all His servants). Associating certain titles with certain personages only, does not make them exclusive or unique in any way. We honour all in varying terms.
The word Masih only means "the annointed one" and all the prophets of God were annointed as they were appointed in their role of guiding the people. However, Allah retained this name exculsively for Jesus as he retained the title of "friend of Allah" for Abraham and " one who spoke with Allah" for Moses. Now that doesn't mean that all the Prophets were not annointed, were not friends with Allah or did not speak with Allah, it's just some titles were given to certain prophets. It does not mean one is honoured over the other. Yes, in ranking, Abraham is higher than Jesus in the sight of Allah, but for Muslims, we see them as equals and we love them all the same!
Indeed the title is never used in the Qur'an without the definite article. This rules out any possibility that the title can be applied to anyone else.
This word Masih does not need a definition because it is a
word that is understood and was understood by the people of old. It was a common term that the Arabs and Jews alike used! I don't know if I can put it any simplier than that!