MrXHellboy

Wrap abbreviations for search engine optimization and support other applications
Using abbreviations on your website is not a bad idea since people will get tired of reading the same over and over again. 
Unfortunately, search engines and other application which might render your website are not that great with abbreviations. 
Reading software, spelling checkers, language translations or other applications might fall over them.
By wrapping abbreviations in the therefor “abbr” HTML element, along with a title(description), applications relying on the structure of your site, can do their job just fine.
Search engines will read the abbreviation and the description which increases the chance for more relevance by specific terms used on search engines like Google.
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Abbreviations for WordPress

Wrap abbreviations for search engine optimization and support other applications

Hailstorm

WCAG 1.0 Guideline 4: Clarify natural language usage. Content developers should provide expansions of abbreviations and acronyms.

Accessibility Abbreviation

Add abbreviation-tags via TinyMCE to comply with the Web Content Accessibility Guidelines.

Abbreviations for WordPress vs Accessibility Abbreviation