term:

Surprise

surprise n

1 : a condition or situation in which a party to a proceeding is unexpectedly placed without any fault or neglect of his or her own and that entitles the party to relief (as a new trial)
2 : an aspect of procedural unconscionability that consists of hiding a term of a contract in a mass of text

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.