A creditor's claim in bankruptcy is either:
A right to payment from a debtor or its property, whether or not liquidated (www.practicallaw.com/3-382-3588) or unliquidated, fixed or contingent, matured or unmatured, disputed or undisputed, legal or equitable, secured or unsecured.
The right to an equitable remedy for breach of performance if such breach gives rise to a right of payment. For example, an environmental cleanup order is a claim if a money judgment is imposed to enforce the cleanup order against the debtor.
Congress intended to give "claim" an expansive definition to capture all of the debtor's legal obligations, no matter how remote or contingent, and have them resolved in the bankruptcy case (§101(5), Bankruptcy Code).