The template {{defn}} is used in template-structured glossaries to create definitions of terms.
It is a wrapper for <dd>...</dd>, the description list definitionHTML element. The template has a mnemonic redirect at {{dd}}.
Links, inline templates, reference citations, wikimarkup styles, etc., can be applied to the definition. Technically, the |1= part is optional if the content of the definition does not contain the "=" character, but as any editors can add content, including templates with this character in them, it is always safest to explicitly name the parameter. The |1= parameter can also be called |defn= for those who don't care for numeric parameters.
This will work: {{defn|1=The concept that the mass of a body is a measure of its energy content, expressed by the formula E=MC²}}
This will work: {{defn|defn=The concept that the mass of a body is a measure of its energy content, expressed by the formula E=MC²}}
This will fail: {{defn|The concept that the mass of a body is a measure of its energy content, expressed by the formula E=MC²}}
More complex usage might be:
{{defn|1=Definition. |no=# |term=term_id}}
where |no=# gives a leading number for a definition in a list of definitions, and |term=term_id provides the name of the term used in the {{Term}} template to which this definition pertains.
Images, hatnotes and other content
Images, hatnotes and other "add-in" content intended to immediately follow the {{term}}must be used at the top of (inside) the first {{defn}} of the {{term}}. They cannot be placed between the {{term}} and {{defn}} or it will break the glossary markup. Images can, of course, be placed elsewhere within the {{defn}}, and bottom-notes like {{more}} can be placed at the ends of but inside the content of {{defn}}s.
{{glossary}}{{term|1=colour ball |content=colour ball {{anchor|coloured ball|coloured balls|colour|colours|color ball}}}}{{defn|1=[[File:Set of Snookerballs.png|thumb|right|150px|A complete set of snooker balls, with six '''colour balls''']]{{ghat|Also '''coloured ball(s)''', '''colour(s)'''; American spelling '''color''' sometimes also used.}}
In [[snooker]], any of the {{cuegloss|object ball}}s that are not {{cuegloss|red ball|reds}}.
}}{{glossary end}}
A complete set of snooker balls, with six colour balls
colour ball
Also coloured ball(s), colour(s); American spelling color sometimes also used.
If a single {{term}} has multiple definitions, they are simply numbered with the |2=parameter explicitly. Think of the parameter as standing for "2nd or later definition". You can also call it |no=, if you prefer (from "No.") Example:
{{glossary}}{{term|1=blubbermonster}}{{defn|1=Lorem ipsum dolor sit amet. |no=1}}{{defn|1=Consectetur adipisicing elit. |no=2}}{{glossary end}}
blubbermonster
1. Lorem ipsum dolor sit amet.
2. Consectetur adipisicing elit.
Because of the uneven length of definitions, it is usually more convenient to put the |2= before the |1= description:
{{defn |2=1 |1=Lorem ipsum dolor sit amet.}}
or
{{defn |no=1 |1=Lorem ipsum dolor sit amet.}}
This is a very robust method, because it permits complex content like block quotations, nested lists, cross-reference hatnotes, and other block-level markup inside each definition. The definitions can also be independently linked.
Use of a "standard" hatnote with a numbered definition would require manual numbering or it would look weird. But this method is deprecated anyway. An example of forcing it to kinda work:
{{term|1=blackjack|content=blackjack{{anchor|Blackjack}}}}{{defn|1={{main|Blackjack}}}}{{defn|no=1|1=A card game in which players attempt to approach 21 but not exceed it.}}{{defn|no=2|1=The best possible hand in the game of blackjack, made up of an ace and a card valued at 10 (namely, 10, J, Q, K). }}
It's better to use the {{ghat}} template, for glossary hatnotes, and put it inside the first (or most applicable) definition. This obviates creating a pseudo-definition to hold the hatnote, as shown above. {{Ghat}} (which uses Module:Hatnote inline) has some CSS adjustments to work better than {{Hatnote}} and its derivatives, when used inside a definition.
Making the definition independently linkable
HTML5 update:
Most of the restrictions on the content of id have been removed, so id values no longer have to begin with an [a-z][A-Z] alphabetic character, avoid most punctuation marks, or suffer other such limitations. Wikipedia's MediaWiki engine is smart enough to auto-escape any problematic characters, on the fly.
To enable a link directly to a specific definition, name the definition with its {{term}} (or it must be the |id=foo value, if any, used in {{term}}). This must be unique on the page for each term, but should be the same for multiple definitions of the same term). This is done with the {{defn}}'s |term= parameter. This will produce a #-link target ID in the form term-defn#, where the # is the number of the definition (see #Multiple definitions for one term, above), defaulting to "1". Example:
{{glossary}}{{term|1=blubbermonster}}{{defn|no=1 |1=Lorem ipsum dolor sit amet. |term=blubbermonster}}{{defn|no=2 |1=Consectetur adipisicing elit. |term=blubbermonster}}{{term|1=snorkelweasel (noun)}}{{defn|1=Ut enim ad minim veniam |term=snorkelweasel (noun)}}{{glossary end}}
blubbermonster
1. Lorem ipsum dolor sit amet.
2. Consectetur adipisicing elit.
snorkelweasel (noun)
Ut enim ad minim veniam
HTML output:
<dlclass="glossary"><dtclass="glossary"id="blubbermonster"style="margin-top: 0.4em;"><dfnclass="glossary">blubbermonster</dfn></dt><ddclass="glossary"id="blubbermonster-defn1">1. Lorem ipsum dolor sit amet.</dd><ddclass="glossary"id="blubbermonster-defn2">2. Consectetur adipisicing elit.</dd><dtclass="glossary"id="snorkelweasel_(noun)"style="margin-top: 0.4em;"><dfnclass="glossary">snorkelweasel (noun)</dfn></dt><ddclass="glossary"id="snorkelweasel_(noun)-defn1">Ut enim ad minim veniam</dd></dl>
Note that some characters in snorkelweasel (noun)" have been converted on the fly by MediaWiki by the time it sends the ID to the browser as snorkelweasel_.28noun.29-defn1. You can still link to it on this page as #snorkelweasel (noun)-defn1 (view page source and see for yourself – that link has href=#snorkelweasel_.28noun.29-defn1).
The IDs blubbermonster-defn1, blubbermonster-defn2, and snorkelweasel_(noun)-defn1 are all individually linkable, e.g. as [[Glossary of weird terms#blubbermonster-defn1]]. This is especially useful for cross-references within the glossary, e.g. See also [[#blubbermonster-defn2|"blubbermonster", sense 2]].
To add more than one linkable anchor, use the {{anchor}} template at the beginning of the definition's content:
There is no |lang= parameter, as on English Wikipedia all definitions are necessarily in English. For uses of glossary markup for non-glossary purposes in which some content may be in a foreign language, use language templates. E.g. in a list of film title translations formatted using glossary markup:
{{glossary}}{{term|1=Titles of La Vie en Rose in various languages |content=Titles of ''[[La Vie en Rose]]'' in various languages}}{{defn|1=French: ''{{lang|fr|La Vie en Rose}}''}}{{defn|1=English: ''Life in Pink''}}
...
{{glossary end}}
Examples
This shows both a very simple then a rather complex instance:
Markup
== A–M =={{glossary}}{{term|1=applesnorkel}}{{defn|1=Definition of term 1.}}{{term|term=arglefarst |content={{lang|xx|arglefarst}}{{anchor|argle-farst|argle farst}}}}{{defn|no=1 |defn=
Beginning of first definition of term 2
{{quote|1=Block quotation in first definition of term 2.}}
Conclusion of first definition of term 2.
}}{{defn|no=2 |defn=Second definition of term 2.}}{{glossary end}}
Renders as
A–M
applesnorkel
Definition of term 1.
arglefarst
1. Beginning of first definition of term 2
Block quotation in first definition of term 2.
Conclusion of first definition of term 2.
2. Second definition of term 2.
Applying CSS styles to the definition
The |style= parameter will pass CSS styling on to the <dd> element, e.g. |style=font-family:serif; or whatever. I.e., this styles the definition itself, not the term it applies to, other definitions, or the glossary as a whole. This feature is rarely if ever needed in articles, but can be useful elsewhere for things like matching custom user page style.
Other parameters
The |id= parameter can be used to assign a one-word, case-sensitive ID name to definition. It must be unique on the page. This can be used as a #link target, and could have other metadata uses. See the #Making the definition independently linkable section for how to normally make a definition linkable. Probably the only reason to use this feature is if there are two terms with the same name on the page, which would result in conflicting IDs.
The |class= parameter will pass one or more space-separated CSS classes on to <dd> element. There is rarely any reason to do this.
Note: With the use of TemplateStyles in the enclosing {{glossary}} (which generates the HTML <dl class="glossary"> tag), this template no longer includes the glossary class by default.
{{glossary}} a.k.a. {{glossary start}} or {{glossary begin}} – Half of a template pair; uses <dl> with a class to open the structured glossary definition list that {{glossary end}} closes.
{{glossary end}} – The other half of this template pair; uses </dl> to close the definition list that {{glossary}} opens.
{{term}} – The glossary term to which the {{defn}} definition applies; a customized <dt> with a class and an embedded <dfn>.
{{defn}} – The definition that applies to the {{term}}; uses <dd> with a class
{{ghat}} – a hatnote template properly formatted for the top of a {{defn}} definition
{{glossary link}} – meta-template for creating shortcut templates for linking to definitions in specific glossaries
