What is conviction and is it in the Bible?

There are a couple of different meanings for this word, but the one that comes to mind the most is being found guilty of something.  The word conviction is found only one time in the Bible and it is in the past tense in John 8:9.  When the Pharisees brought the adulterous woman to Jesus and asked Him what should be done to her, after Jesus wrote in the dirt some He told them that he who is without sin can cast the first stone.  After this they were all convicted in their hearts of their sins and they all left.  Throughout the Bible we see people who are convicted in their hearts for sins that they have done, however the word itself is not used.  God will convict our hearts of sin so that we can regain our fellowship with Him by confessing these to Him (1John 1:9).