- zipper clause
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zip·per clause n [from the comparison of such a clause to the closing action of a zipper]: a clause in a labor contract indicating that the agreement is an exclusive and complete expression of consent◇ A zipper clause may constitute a waiver of the right to bargain over issues negotiated in or outside the terms of a contract until its expiration.
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.