Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.  John 14:6
Jesus used this name for Himself in a conversation with His disciple Thomas. This is the only place in the New Testament where Jesus is referred to as the Truth.
We usually use the word truth in referring to words or speech. For example, we might pay a compliment to a friend by saying “She always tells the truth.” This use of the word certainly applies to Jesus. He always spoke the truth to His disciples and to others, even when they had a hard time accepting it. This was especially the case with His statements about His coming death (see Matthew 16:21-22).
But beyond speaking the truth, Jesus acted out the truth in His life and ministry. And even more importantly, He was and is the Truth, because He is the ultimate reality in the universe. This is the sense in which Jesus referred to Himself as the Truth in His conversation with Thomas. 
We live in a world in which it is sometimes hard to nail down the truth. Our materialistic society tries to convince us that money and possessions are the essence of truth and the way to the good life. Some people say that learning or knowledge is the ticket to the truth. Others believe that each person has to find truth for himself by constructing it from him own life experiences. What is truth for one person may not be truth for another, these people say, because there is no such thing as absolute truth.
These modern theories remind us of Pilate, the Roman governor who pronounced the death sentence against Jesus. When Jesus told him that He had come into the world to “bear witness unto the truth” (John 18:37), Pilate asked sarcastically, “What is truth?” (John 18:38). The Truth stood so close to Pilate that he could touch it, but he missed it because of his unbelief.
What a tragedy! And what an accurate picture of a sinful and unbelieving world-the arena into which we as Christians are sent to bear witness of the Truth (see Mark 16:15).