Definitions are powerful provisions because they control the meaning of terms used throughout a legislative text and, in the absence of a contrary intention, the meaning of terms in all other enactments relating to the same subject-matter.[1] They have a very strong influence on the interpretation of legislative texts. This article examines these important provisions in the English version of federal legislative texts. It will examine the principles governing the use of definitions and the rules for drafting them.

(Please also see the Legistics article "Attributing Meaning to Terms")

Principles governing the use of definitions

Common meaning of words

Definitions in legislative texts are stipulative; they state what a term is to mean in the text. They are only required if they depart from the commonly understood meaning of the term. Definitions included in legislative texts must never simply reiterate the content of a dictionary or state the obvious. If the meaning of a term is well understood by the intended audience and unambiguous, don't define the term. It is not necessary to define a term simply because it is a technical, scientific or other term of art. Legislative counsel should systematically avoid defining terms that do not depart from their ordinary meaning.

All texts on legislative drafting, from the Uniform Law Conference Drafting Conventions[2] to Driedger[3] and Thornton,[4] argue for restraint in the use of definitions, primarily because they do give an artificial meaning to words. Definitions require a reader to grasp, understand and remember a number of terms that depart from the reader's common understanding of them. This puts a strain on the reader's ability to read and understand the substantive provisions of the text.

Definitions also fragment the text and require the reader to combine separate units of text, which again complicates the reader's task in trying to understand the law. And this problem is aggravated when definitions in other documents apply or are incorporated by reference. Although it is possible to define a term used in a legislative text by reference to a definition in another text, this technique should be the exception rather than the rule. It should be limited to those cases where consistency between the two texts is essential and the definition referred to is likely to be frequently amended.

Definitions should not extend the meaning of words to things that are not ordinarily associated with them. Avoid definitions like the definition of cattle in section 2 of the Criminal Code:

"cattle" means neat cattle or an animal of the bovine species by whatever technical or familiar name it is known, and includes any horse, mule, ass, pig, sheep or goat.

As Thornton states:

"[d]efinition in legislation is only useful so long as it serves the essential purposes of determining and communicating legislation. To serve the purpose of easy communication, a definition must follow customary usage as closely as possible. A definition which places a completely forced and artificial meaning on a term is a bad definition."[5]

Effect of definitions

The Interpretation Act specifies the effect of a definition:

Before a term is defined in a legislative text, all other Acts and regulations dealing with the same subject-matter should be consulted to ensure, where possible, consistency in the use of the term.

Role of definitions

There are three reasons to define a term in a legislative text:

Definitions should be used to avoid uncertainty when

But in these cases it is best to include a modifier with the defined term to indicate something about its limited meaning:

Definitions can be used to explain the meaning of new or unusual words:

There is a risk, however, that defining these terms will not fully capture their meaning. This concern can be alleviated by using a generic definition so that the term's meaning will continue to evolve and the definition will not become outdated. An includes definition may also be an alternative. However, there is always a danger of causing ambiguity if an includes definition is used in these circumstances.

Definitions can be used to shorten long names or phrases or to avoid repetition, for example:

Use of definitions

Words should usually not be defined if they are used only once or twice — the meaning of the term should be incorporated into the provision itself. If a technical term or term of art is used that may not be understood by all readers, an alternative is to place the meaning in brackets after the term


(2) Unless otherwise indicated, when these Regulations refer to the mass of an explosive, they are referring to the net explosives quantity (the mass of the explosive excluding the mass of any packaging or container).

Contents of definitions

A definition must not include any substantive provision. But when is a definition substantive? One test is to look at how much meaning a provision conveys without the definition, for example, in "The Minister may appoint qualified persons as members…." qualified conveys little on its own — the substantive nature of the content should be added in a subsequent sentence: "A person is qualified to be appointed if the person…." On the other hand, in "The Minister may make emergency orders for the purpose of protecting the habitat of a listed wildlife species" habitat conveys meaning on its own. A definition would simply clarify its meaning.

Rules of conduct are substantive and should not be in definitions. Avoid granting a power to a person solely by means of a definition. The following definition should only be used if there is an independent power in the substantive provisions of the text that grants the Minister a power to approve containers:

"approved container" means a container approved by the Minister.

When a word or expression denotes something fundamental to the legislation, its definition is equivalent to an application provision. Consider drafting it as an application provision at the beginning of the text to be read first, rather than as ancillary matter buried among the definitions. This gives a degree of visibility or priority that is appropriate to the fundamental nature of the word or expression. For example, the following provision in section 2 of the Canada Wildlife Act replaced a definition of "wildlife" in that Act:

(4) The provisions of this Act respecting wildlife apply in respect of

  • (a) any animal, plant or other organism belonging to a species that is wild by nature or that is not easily distinguishable from such a species; and

  • (b) the habitat of any such animal, plant or other organism.

Types of Definitions

Delimiting definition

A delimiting definition is exhaustive. It is intended to set limits on the otherwise ordinary meaning of terms. These definitions normally begin with the word "means".


A delimiting definition may be used to abbreviate a lengthy group of words to a single word or a shorter group of words.


Extending definition

An extending definition adds to the ordinary meaning of a term a meaning it does not normally have. These definitions usually begin with the word "includes". This type of definition may be used to broaden the meaning of a term, expressly including elements that would otherwise not normally be included.


Narrowing definition

A narrowing definition narrows the ordinary meaning of a term by setting limits or expressly excluding. These definitions normally begin with the word "means" or the words "does not include".


Mixed definition

A mixed definition may be necessary not only to set limits on the otherwise ordinary meaning of terms, but also to clarify particular elements included in or excluded from the term. These definitions are typically introduced by "means … and includes …" or by "includes … but not does include …."


But the ULC Drafting Conventions, s. 21(4), caution against definitions that mean one thing and include another. They should only be used when an exhaustive definition is required and there are serious doubts about whether it covers particular things.

Of course, a word should not be defined to both mean and include the same thing, i.e., "A" means and includes B.

Drafting Definitions

Other terms used to define

Other wording besides "means" and "includes" may also be used to draft definitions:

Using defined term in the definition

Be careful about including the defined word in the definition as it may create a logical loop. However, this does not generally cause problems when a definition limits the scope of the defined term:

Parts of speech

Interpretive provisions can apply to any part of speech, including phrases. However, nouns are the most commonly defined. A definition of one part of speech usually applies to other grammatical forms of the same word. This is confirmed in section 33 of the Interpretation Act:

(3) Where a word is defined, other parts of speech and grammatical forms of the same word have corresponding meanings.

Contents of definitions

Definitions should, as far as possible, be complete in themselves. Definitions that simply refer to another provision of the text or to another text can be annoying because they simply send the reader to another provision or text to find out what the word means. However, if it is necessary to refer to other provisions or a definition in another text, try to give a generic meaning in addition to the reference. For example,

"waiting period" means the two-week period referred to in section 66 for which unemployment benefits are not paid.

is more informative than

"waiting period" means the period referred to in section 66.

To keep the main rule of conduct uncluttered it may be desirable to state the rule then explain the meaning of terms used in the rule in definitions that follow. For example, instead of

100. Any vehicle or receptacle in which explosives are conveyed from one building to another in a magazine, or from any building to any place outside of a magazine, or from one part of a magazine to any place outside of a magazine, other than a vehicle or receptacle in which only explosives of Division 1 of Class 6 (ammunition) are conveyed, shall be constructed without any exposed iron or steel in its interior.


100. (1) A transport unit, other than a transport unit in which only explosives of Division 1 of Class 6 (ammunition) are conveyed, shall be constructed without any exposed iron or steel in its interior.

(2) A transport unit is any vehicle or receptacle in which explosives are conveyed from one building to another in a magazine, or from any building to any place outside of a magazine, or from one part of a magazine to any place outside of a magazine.

Multiple defined terms

Avoid multiple defined terms such as

"magazine" and "storage unit" mean any building, storehouse, structure or place in which explosives are kept or stored.

When definitions are arranged alphabetically, a reader looking for the definition of "storage unit" is unlikely to think of looking under "m". These definitions also violate the consistency rule of drafting — different words should have different meanings.

Formal Aspects

Definitions are drafted in the form of "Act" means …, "action" includes ….

The defined words are enclosed in "quotation marks" and are not capitalized unless they are capitalized generally. If there is only one definition in the provision, it should be a single sentence:

2. In this Act, "institution" means any international financial institution named in the schedule.

Definitions that apply throughout an Act or regulation should be in a separate section near the beginning of the text with a heading or marginal note that says "Interpretation" or "Definitions" ("Definitions" may be used if there are only defined terms with no other interpretive provisions). If defined terms relate only to a particular part, division or group of sections, they may be put at the beginning of the part, division or group. If they relate to a single section, they may be placed in a subsection either at the beginning or the end of the section. Placing them at the beginning of the section, however, may give them undue prominence and, if marginal notes are included for each subsection, the first note for the section will not indicate the contents of the section (it will say "Definitions").

If there is more than one definition, the provision should be introduced by the opening words:

1. The following definitions apply in this Act/these Regulations/this Part.

Each definition should be one or more sentences. In older Acts and regulations, definition provisions were drafted as a single sentence with the following opening words, "1. In this Act/these Regulations/this Part,". The current practice is preferred because it recognizes that each definition stands on its own, and it allows multiple sentences for complex definitions.

Definitions are grouped alphabetically within their own language group. They are not numbered. The equivalent word in the other language version is indicated in French quotation marks (« … ») and italics in the marginal note or in parentheses and italics at the end of the definition in legislative texts that have no marginal notes. For example:

« commissaire »

"Commissioner" means the Commissioner of the Royal Canadian Mounted Police.

"Commissioner" means the Commissioner of the Royal Canadian Mounted Police.

If there is no equivalent word, the phrase "Version anglaise seulement" (meaning "English version only") is used instead. If the definition section contains only one definition, the introduction and the equivalent French term are omitted.

If a definition applies to two alternative forms of the same defined term, each alternative is placed within quotation marks.


"in vitro diagnostic device" or "IVDD" means a medical device intended to be used …. (instrument diagnostique in vitro ou IDIV)

Note that the equivalent French terms, including the word ou, are in italics when the term appears at the end of a definition in regulations.

A general definition section that applies to the legislative text as a whole usually appears at the beginning of the text and should have the following format:


1. The following definitions apply in these Regulations.

If the definition is divided into paragraphs and subparagraphs, the defined term and any necessary opening words appear on the first line, and the usual rules respecting the division of text into paragraphs and subparagraphs apply.


"machinery spaces of category A" means

  • (a) spaces that contain

    • (i) internal combustion-type machinery used for main propulsion or, where the aggregate of total power output is not less than 373 kW, for purposes other than main propulsion,

    • (ii) an oil-fired boiler, or

    • (iii) a fuel oil unit; and

  • (b) trunks to spaces referred to in paragraph (a).

Paragraphs are normally separated by semi-colons and subparagraphs by commas.

Cross-references in the text to definitions are made by saying, "the definition " word "in section 2".

Amendments to Definitions

In an amending Act or regulation, amendments to definitions should come into force concurrently with the substantive amendments to which they relate. For instance, if a substantive amendment containing a defined term comes into force on a named date, an amendment made to the defined term should come into force on the same date, even if that means creating a separate subsection for the amendment of the definition.

If a definition is being added to a definition provision drafted in the old style or a definition in such a provision is being replaced, the old style must be followed.

Alternatives to Formal Definition Sections

It is not necessary to always use a formal definition to set out the meaning of a term in a legislative text. It is possible to use interpretive provisions that say something about the meaning of words, but which are drafted as regular provisions without focusing on quoted words. This may be done when