Voidable

adj. can be voided; can be canceled, annullable

In law, a transaction or action which is voidable is valid, but may be annulled by one of the parties to the transaction. Voidable is usually used in distinction to void ab initio (or void from the outset) and unenforceable.The act of invalidating the contract by the party exercising its rights to anul the voidable contract is usually referred to either as voiding the contract (in the United States and Canada) or avoiding the contract (in the United Kingdom, Australia and other common law countries).Generally speaking, one party will have the right to elect whether to annul the transaction or to affirm it. The avoiding of a voidable transaction amounts to the rescinding it, or exercising a power of rescission, and as such is subject to the general law in that regard.
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Adjective
1. capable of being rescinded or voided; "the judgment was rescindable"; "voidable contracts"
(synonym) rescindable
(similar) revocable, revokable

(a.)
Capable of being voided, or evacuated.
  

(a.)
Capable of being avoided, or of being adjudged void, invalid, and of no force; capable of being either avoided or confirmed.
  

The law distinguishes between contracts which are void and those which are voidable. - (read more on Voidable)