Glossary

Commercial Insurance Glossary

The terms that actually determine whether you are covered, defined in plain English rather than policy language.

Commercial insurance has a vocabulary problem. Most definitions available online are written for insurance professionals, which means they explain a term using four other terms you also do not know. This glossary is written the other way around, for the business owner or operator who needs to understand what a policy actually does before signing something.

Terms marked with a badge have a full explainer page. The rest are defined here in enough detail to be useful.

Program structure

Insurance Stackalso: Stack, coverage stackFull page: The complete set of commercial insurance coverage lines protecting a business, treated and managed as a single program rather than a collection of separately purchased policies. Managing insurance as a stack matters because most coverage failures happen between policies rather than inside any one of them. Read the full definition, including what belongs in a stack and how to review one
Coverage linealso: line of coverage, line of business: A single type of insurance within a program, such as general liability, cyber liability, professional liability, or workers' compensation. Each line responds to a different category of loss, and a business needs the lines that match what it actually does.
Exclusion: Policy language removing a risk from coverage. Coverage is defined more by its exclusions than by its insuring agreement, which is why any serious program review starts with the exclusions rather than the summary page.
Coverage gap: A loss scenario where no policy responds, usually because two policies each exclude it and the business assumed the other one covered it. Gaps are invisible until a claim tests them, which is what makes them dangerous. Employment claims, professional errors, and electronic data loss are the three most common places gaps form.
Coverage overlap: When two or more policies cover the same exposure. Deliberate overlap can be useful, since it prevents a claim from falling between policies. Unintentional overlap usually means paying premium twice for the same protection, and can delay a claim while two carriers argue over which responds first.
Other insurance clause: Policy language determining which policy responds first when more than one could cover the same loss. This is the provision that resolves overlaps, and conflicting clauses across policies are a common cause of delayed claim payments.

Retentions and limits

Deductible: An amount subtracted from a covered loss before the carrier pays. The carrier's obligations, including its duty to defend, typically attach from the first dollar, and it recovers the deductible from you afterward.
Self-insured retentionalso: SIR: An amount you pay before coverage responds at all. The practical difference from a deductible is when the carrier's obligations begin, which affects who controls and funds the defense of a claim in its early stages. Compare self-insured retention and deductible in detail
Stacking of limits: Applying the limits of two or more policies, or two or more coverages within one policy, to a single occurrence or claim. This is a claims and coverage litigation concept, argued most often in uninsured motorist, construction defect, and long-tail pollution cases, and frequently restricted by anti-stacking provisions. It is a different concept from an insurance stack, which describes the portfolio of coverage lines a business carries.
Umbrella and excess coverage: Additional limits sitting above your underlying liability policies, responding once those limits are exhausted. Most often purchased because a customer or landlord contract requires limits higher than your primary policies carry.

Contracts and evidence

Certificate of insurancealso: COI: A summary document evidencing that coverage is in force, requested by customers, landlords, and partners to confirm you meet their contractual insurance requirements. A COI is evidence of coverage, not coverage itself, and it is where deals most often stall at signature. Check whether your COI is likely to be rejected
Additional insured: A party extended coverage under someone else's policy by endorsement. This is the most commonly required and most commonly missing element on a certificate of insurance, and its absence is the single most frequent reason a COI gets rejected.
Primary and noncontributory: Contract wording requiring that your policy respond first and without seeking contribution from the other party's insurance. Frequently demanded in customer and landlord agreements, and it must be added by endorsement rather than assumed.
Waiver of subrogation: A provision under which your insurer gives up its right to recover from a third party that caused a loss. Commonly required in commercial contracts so that a partner is not pursued by your carrier after an incident.

Risk management

Risk transfer: Moving the financial consequence of a loss to another party, typically an insurance carrier through a policy or a counterparty through contractual indemnity. The risk still exists. The bill lands elsewhere.
Risk mitigation: Reducing the likelihood or severity of a loss through controls, training, processes, and technology. Distinct from risk transfer: mitigation makes a loss less likely, transfer determines who pays when it happens anyway.
Risk retention: Absorbing a loss yourself rather than transferring it. Deliberate retention through deductibles and self-insured retentions is sound program design. Discovering an uninsured exposure after a loss is accidental retention, which is the same outcome without the planning.
Risk register: An internal inventory of risks a business has identified, usually maintained in risk management or GRC software with scoring and assigned owners. A register documents exposure. It does not transfer it. A risk in the register with no matching coverage line is a documented uninsured exposure. How risk software and a broker divide this work
Total cost of riskalso: TCOR: The full economic cost of risk to a business, not just premium. It comprises insurance premiums, retained losses paid out of pocket, the cost of risk control measures including software and staff, and program administration. TCOR is the number both insurance and risk tooling should be evaluated against.

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