Like a dictionary? Christianity is not a religion, but rather a relationship between man and God. The Bible describes this relationship in great detail as well as how this relationship (God and Man) relates to the word of God. The Bible is clear that those who teach contrary to the Word of God, are not of God. The Bible is also clear that His people since the Resurrection has been those who've enetered into a relationship with Him by belief in Christ's scrifice.
So, the Bible is quite clear about (what a "Christian" is), the relationship one is to have with God, how a person in this relationship is to live, and how a person in this relationship uses the Word of Lord. Anything contrary to this is not, Christian.