"Now FAITH is the substance (the confirmation, the title deed) of things [we] hope for, being the proof of things [we] do not see and the conviction of their reality [faith perceiving as real fact what is not revealed to]"
Faithfullness is described as dependable, loyal and full of trust.
When I think of faithfullness I think of Abraham. God had told him that he would be the father of many nations. This was a promise from God and Abraham believed this would come to pass. At the time he was already an old man. Finally his son was born when he was one hundred years old. But I have oftened wondered why he didn't doubt the promise during those years of waiting. It's because he faithfully believed God's word that what He said He would do, would happen.
We must put our trust in the Lord. In Proverbs 3: 5-6 it says. "Trust in the Lord with all your heart and lean not on your own understanding; in all your ways submit to him, he will make your paths straight." I think for me faithfullness is all about putting my trust in the Lord.
One example of God's faithfullness in my own life was when I gave up work to serve the Lord for a year. I knew that He had called me and it would mean relying on Him for all my provision but I also knew that as I was faithful to that call to trust Him He would take care of all my needs. Which is exactly what happened!
"Great is His faithfullness, morning by morning new mercies I see."