The Hebrew word for faith is Emunah. The root of this word is Emun which means truth, solid, sure, support. Faith is a surety of what is not seen being true and solid. Emunah also means steadfast, established, and stable. The more faith you have, the more established and stable the object of your faith becomes in your life. When you have faith in God, He becomes stronger and more established in your life.
Another word that comes from the same root word is amen. It sounds like emun or emunah. To say amen is to say "That is true." "Yes, I have faith in that." Faith is to say amen to God. It is to say amen to God's salvation. Amen to His love. Amen to the reality of God.
Saying Amen is to say, "My whole being, my heart and my soul stand steadfast in the knowledge that what God says is true. I stand on His word which is a solid rock that shall never fail me. Here I stand, I can not do otherwise."