In contract law, there is a doctrine called unconscionability that deals, essentially, with unfair contracts. Unfairness implies something slightly less than is required for unconscionability but it’s the best lay term I can think of. A contract can be procedurally unconscionable (meaning the manner in which it is agreed is unreasonable), or substantively unconscionable (meaning the terms are unreasonable).
The classic law school unconscionability case is Williams v. Walker-Thomas Furniture, 350 F.2d 445 (D.C. Cir. 1965). A store that sold household goods on instalment contracts had a provision that (simplifying) said they could seize everything they sold you if you missed a payment on one item. A single mother missed a payment on a radio and they basically came and reposessed all the contents of her house. The court tossed the contract.
In the OP, you have a contract that might be both procedurally and substantively unconscionable. Burying a major term in fine print is a classic example of procedural unconscionability. The other party deceiving you about the contents of the contract so you don’t read it is another. Is the contract one of adhesion? That is, is there an opportunity to negotiate? For example, an apartment lease is usually a contract of adhesion because the apartment complex won’t rent to you if you scratch out the “no pets” clause. Relative bargaining power is another factor. In Williams, the store was the only place that offered sales to African-Americans in the town on credit, so they had no other options. Whether the parties are both sophisticated negotiators is another factor. Did you have a lawyer look over the contract before you signed it? Are you a businessperson who deals with contractual matters on a frequent basis? If so, you are more likely to have the contract enforced against you.
Inserting a completely one-sided and punitive provision like that is a good example of substantive unconscionability. Substantive unconscionability is simpler: is the contract so ridiculously one sided that enforcement would be unjust? In Williams, the contract was substantively unconscionable because it allowed the store to seize everything even if only one item was in default. Penalty clauses are allowed in contracts, but they must generally be proportional. You can contract for liquidated damages (that is, a set figure payable on breach) but not for five times the value of the contract itself.
ETA: ninja’d by Richard Parker.