1. noun
a) A formal plea by a defendant of not being culpable for the crime with which the defendant is charged.
If you do not plead, a plea of not guilty will be entered for you.
b) A verdict or formal finding by the legal system that a defendant is not culpable for the crime with which the defendant was charged.
2. adjective
a) Of a person, legally innocent of a crime which they have been accused of in a court of law.
He was found not guilty because there was a reasonable doubt.
b) Innocent.
The jury said he was not guilty. I knew he wouldnt have done something like that.
Wikipedia foundation.