I love this definition from a recent BAP case, Fountain v. Deutsche Bank National Trust Company (In re Fountain), — B.R. —  (9th Cir. BAP  Mar, 2020)

A debt is contingent when “the debtor will be called upon to pay [it] only upon the occurrence or happening of an extrinsic event which will trigger the liability of the debtor to the alleged creditor.” Fostvedt v. Dow (In re Fostvedt), 823 F.2d 305, 306 (9th Cir. 1987). If “all events giving rise to liability occurred prior to the filing of the bankruptcy petition,” the claim is not contingent. In re Nicholes, 184 B.R. at 88. A dispute over liability for a claim does not make the debt contingent. Id. at 89 (citing In re Dill, 30 B.R. 546, 549 (9th Cir. BAP 1983))

In my world, this comes up most often when an individual has guaranteed his business loans, i.e., corporate debts.  Is his personal obligation to the bank contingent?  Of course says I.  And the above quote supports that position.  The individual is called on to pay the debt only when the corporate entity has failed to pay it.  But in fairness, you have to read the words of the “guaranty.”  In commercial corporate guarantees, the ones I have read at least, the individual typically waives any rights he may have to require that the bank go after the corp first.  The guaranty is likely to say that the bank can ignore the actual borrower entirely and go after the individual if that’s what it chooses to do.   That may not be a contingent debt.