Where and how should this term be stored? Within plain wikitext on the wiki, within a Scribunto Data Module, or within Wikidata?

A Scribunto implementation might look like this

glossary = {
  ['term'] = {
    -- A term has zero to many language equivalents
     ['en'] = {
        --  A term has one to many definitions
         [1] = { ['definition'] = 'Some defintion',  ['aliases'] = {'first synonym', 'second synonym'}, -- A term has zero to many synonyms
         [2] = { ['definition'] = 'Some other defintion',  ['aliases'] = {'other first synonym', 'other second synonym'},
     } 
     ['eo'] = {
        --  no equivalent for first definition in this language
         [2] = { ['definition'] = 'Iu difino,  ['aliases'] = {'alia una sinonimo', 'alia dua sinonimo'}, 
     }
  ['term2'] = { -- an other entry, filled with an similar structure as the previous one
  }
}

The pro is that it is far more flexible regarding the data rendering. The con is that I have no idea how hard this would be to manage such a structure within the translation extension, I don't think it is treatable as is with the current state of the extension.

I'm not a developer, but I see that glossary as something separate where
translators can find terms. A dictionary.

Sure, but would such an approach be adopted this is not the form most users would consult the glossary, it just make it more structured with all the pro and cons of such an approach. Just like wikidata in fact.

Glossary needs to contain both software and project terms.

• Software term glossary should be used from Translatewiki, from Mediawiki.org and from Meta (for technical help).
• Project term glossary should be used mainly from Meta.

Note that all localization project have implemented their own glossary service. See Mozilla, Drupal, Wordpress, KDE, Transifex, Crowdin… We should not have to reinvent the wheel, but to think about how to connect a glossary service to both TranslateWiki and Wikimedia project galaxy.

In T150263#4844946, @Pols12 wrote:

Note that all localization project have implemented their own glossary service. See Mozilla, Drupal, Wordpress, KDE, Transifex, Crowdin… We should not have to reinvent the wheel, but to think about how to connect a glossary service to both TranslateWiki and Wikimedia project galaxy.

Then one concrete task for someone would then be to check out one or multiple those services and write a summary how they work, are the open source, etc.

There is task for glossary support in Translate: T52092: Implement glossary (terminology) support. Whatever will be implemented, it should be easy to use it in our translation extensions.

Uninteresting:

• Drupal uses Drupal Localization Server which doesn’t provide any glossary service. French community have a glossary website which is currently down.
• WordPress uses GlotPress which integrates a glossary feature. However, its API is currently read-only.
• KDE has no web l10n interface in its website. It only includes a translation search engine but I haven’t found its source code.

Interesting:

• Mozilla uses Pantoon software. There is no integrated glossary service. However Transvision website (which provides RESTful API) let’s search through several translation repositories.
• Pootle seems to be the only l10n platform to have a distinct glossary service, which is called Terminator
• Weblate l10n platform integrates a glossary service and provides a RESTful API. However, glossary endpoint is not documented and may not exist.
• Zanata l10n platform provides a glossary service which is accessible through a RESTful API.

To summarize:

• Terminator is the only dedicated glossary management service I’ve found, but is probably outdated.
• Zanata is a full localization platform with an integrated glossary management service.
• Transvision manages full strings (not only terms) but is interesting because it gets translation from several distinct sources.

Some related links (maybe put some of these in the task description?).

• https://meta.wikimedia.org/wiki/Glossary

• https://en.wikipedia.org/wiki/Wikipedia:Glossary and dozens more: https://www.wikidata.org/wiki/Q1389361#sitelinks-wikipedia

• https://translatewiki.net/wiki/Terminology
• https://translatewiki.net/wiki/Terminology/mediawiki

• https://www.mediawiki.org/wiki/Manual:Glossary
• https://www.mediawiki.org/wiki/Help:Notifications/Glossary
• https://www.mediawiki.org/wiki/Help:Edit_Review_Improvements/Glossary
• https://www.mediawiki.org/wiki/Help:Structured_Discussions/Glossary

• https://wikitech.wikimedia.org/wiki/Help:Glossary

And for the last item in the description ("A user may want to search for a term ..."), these would be among the links I'd initially want easy access to:

• https://codesearch.wmflabs.org/search/?q=Sujet&i=nope&files=&repos=
  • to find https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/Flow/+/master/Flow.namespaces.php
• https://translatewiki.net/w/i.php?title=Special:SearchTranslations&query=sujet&group=mediawiki&grouppath=mediawiki
• https://translatewiki.net/w/i.php?title=Special:SearchTranslations&query=sujet&group=ext-flow&grouppath=mediawiki%7Cext-0-all%7Cext-flow
• https://translatewiki.net/wiki/Special:Translations?message=Flow-link-topic&namespace=8

One additional glossary link to add to the list: https://www.mediawiki.org/wiki/Help:Extension:Translate/Glossary

Translatewiki.net has defaulted a new Terminology gadget: https://translatewiki.net/wiki/Project:Terminology_gadget