Definition from Nolo’s Plain-English Law Dictionary
Something that is taken away or subtracted. Under an insurance policy, for example, the deductible is the maximum amount that an insured person must pay toward his own losses before he can recover from the insurer. For example, Julie's car insurance policy has a $500 deductible. One day she forgets to set her parking brake and the car rolls backwards into a telephone pole, sustaining $2,500 in damage. Julie's insurance company deducts $500 from the total amount and issues a check to the auto body shop for $2,000.