The amount that the insured has to pay before the original coverage plan starts. Insurance companies normally include a deductible in insurance policies to avoid paying on small or minimal claims.
For Example, a car insurance policy contains $500 or $600 deductible. Your car hits another car accidentally. Both of you agree that the loss/damage is very small or minimal and you pay him $500 compensation. After paying for this damage, additional damage would be covered by the insurance company.