@Fido,
I believe the word you are looking for is 'Amendment'.
The word 'slavery' is NOT in The United States Constitution.
The word 'slavery' is in an amendment to The United States Constitution.
It breaks down like this:
The United States Constitution was adopted on September 17, 1787.
The Thirteenth Amendment to the United States Constitution was adopted on December 6, 1865.
The Thirteenth Amendment officially abolished and continues to prohibit 'slavery' and involuntary servitude, except as punishment for a crime.