Definitions clause

Category: Policy structure · Reviewed by the Apex broking team · Last reviewed 2026-08-22 · ~3 min read

Definition

A definitions clause — sometimes headed “Definitions”, sometimes “Interpretation” or “Meaning of words” — lists terms that carry a specific contractual meaning throughout the policy. Defined terms are normally signalled typographically, by capitalisation, bold or italics, and the clause will say so. Once a word is defined, its ordinary meaning is displaced: what matters is the contractual meaning, everywhere the term appears, including inside the exclusions and the conditions.

Why it is the operative part of the contract

The insuring clause of a modern policy is often only a sentence or two, and almost every substantive word in it will be a defined term. The insuring clause promises to indemnify the Insured against Claims first made during the Period of Insurance arising from the conduct of the Professional Services. Every capitalised word there is doing work. Widening or narrowing any one of them changes the scope of cover without touching the exclusions at all. That is why a wording review that reads the insuring clause and the exclusions but skims the definitions will miss most of what matters.

The definitions that decide disputes

A handful recur. Claim determines what has to be notified and when the claims-made trigger is met — whether a demand, a letter before action, a regulatory investigation or a mere allegation counts. Circumstance determines what can be notified before a claim exists, and therefore whether a later claim attaches to this year’s policy or next year’s. Insured determines who is covered, including former partners, employees, consultants and acquired entities. Professional Services determines which of a firm’s activities the policy responds to, and is the definition most often left describing what the business did three years ago. Period of Insurance, Territory, Damage, Property, Loss and Data all do similar work in other classes.

How definitions interact with exclusions

A well-drafted policy achieves through definitions what a poorly drafted one attempts through exclusions. If Property is defined to exclude electronic data, no data exclusion is needed. If Claim is defined to require a written demand for compensation, no exclusion for informal complaints is needed. The practical consequence is that reading the exclusion list on its own gives a misleadingly generous picture of cover, and that two policies with identical exclusion lists can differ substantially in what they insure.

Common traps

Four recur in commercial placements. A defined term used in the schedule with a different sense from the one in the definitions clause. A definition that cross-refers to another defined term, which cross-refers back, so that the boundary is circular. A term that is capitalised in the wording but never defined, or defined but never used. And an endorsement that changes the operative wording without changing the definition it depends on, leaving the two inconsistent. All four are found by reading the definitions against the schedule and endorsements, and all four are much cheaper to fix before inception.

How they are construed

Definitions are construed like any other contractual term: in their documentary and commercial context, giving the words their natural meaning, and reading the policy as a whole. Where a definition is genuinely ambiguous, the ambiguity may be resolved against the party that put it forward, but the modern approach treats that as a last resort rather than a starting point — see contra proferentem. A definition that is clear but unattractive will be applied as written.

What to do at renewal

Take the definitions clause and read it against the business as it is now, not as it was when the policy was first placed. Has the activity list in Professional Services kept pace with what the firm actually sells? Does Insured capture every trading entity, including those acquired or incorporated during the year? Does Territory match where the work is now done and where clients could sue? Then read the same definitions in the excess layers, because a following-form excess policy that has its own definitions is a gap waiting to happen. A short index of the definitions we cover is at definitions index.

Frequently asked questions

Are defined terms really different from ordinary words?

Yes. Once a policy defines a term, that meaning applies wherever the term appears, displacing ordinary usage. That is why capitalised words in a policy should always be read against the definitions clause.

Which definitions matter most?

In a claims-made liability policy, Claim, Circumstance, Insured and the description of the insured activities do most of the work. In property covers, Damage, Property and Period of Insurance carry the equivalent weight.

Can a definition be negotiated?

Frequently, yes. Amending a definition is often a cleaner and cheaper way of fixing a coverage gap than adding an extension, because it corrects the scope at source rather than bolting cover on top.

Related entries

• Definition of claim
• Definition of circumstance
• Definition of insured
• Definition of professional services
• Definitions index
• Exclusion clauses

This entry is part of the Apex Insurance Wiki. Position stated as at August 2026. Last reviewed 2026-08-22. Next review: 2027-02-22. It is general insurance information, not legal advice, and not regulated advice on a specific policy.

Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority (FRN 724952). This page is general information, not advice on a specific policy.