Abbreviations
Every abbreviation needs its expanded form or its meaning available to the reader. Meaning, not only expansion, and for one whole family that distinction decides the answer. Abbreviations borrowed from another language are better explained than expanded, so a.m. should be given as before noon rather than as ante meridiem, which tells an English reader nothing they did not already know.
Why it matters
W3C sets out four separate ways an abbreviation trips a reader. Some cannot be pronounced at all, like rm for room. Some mean two things in one sentence, as in Dr. Johnson lives on Boswell Dr. Some collide with an ordinary word, so JAWS is a screen reader and also part of a mouth. And some sound like a word they are not spelled like, which is why SMIL gets said as smile. Every one of those is harder to hear than to read.
Who this rule protects
People who find words hard to decode, people with limited memory, people who struggle to use context, and readers using a screen magnifier, who lose the surrounding text that would otherwise explain the term.
How to check it yourself
- List every abbreviation on the page.
- Run each one against the dictionary test. If a common dictionary lists it as a word, it is exempt. Familiarity on its own is not enough.
- Check that what you supply is the useful version. An expansion for most, an explanation for anything borrowed from Latin.
- Where one abbreviation means two things on the same page, check that each occurrence carries its own expansion, because a glossary cannot resolve that.
Failures we see most often
- Acronyms run through the page with no expansion anywhere.
- Familiar abbreviations get skipped on the grounds that everybody knows them, which is not the exemption the criterion offers.
- Latin abbreviations get mechanically expanded, so the reader learns that i.e. means id est and is no better off.
- The expansion lives only in a title attribute, which keyboard and touch users never see.
Who this one is for
Read from this rule's own note above, so the grouping and the note cannot disagree.
- Low visionpeople who can see the screen but not easily
- Cognitive and learningpeople for whom the difficulty is understanding, remembering, or staying with it
How to fix it
- Write the full term first with the abbreviation in brackets after it, which is what most style guides ask for anyway.
- Give the meaning rather than the expansion for anything borrowed from another language.
- Keep the expansion in visible text. The abbr element is fine to use, and W3C moved the title-attribute technique from sufficient to advisory once it was clear that title never reaches keyboard and touch users.
- Where you have combined several documents into one page, expand at the start of each one rather than only at the top.
Step-by-step fix guides (7)
- H28: Explain abbreviations with the abbr elementAdvisory
- G55: Link unusual words to their definitions
- G62: Provide a glossary for specialized terms
- G70: Offer a dictionary search for specialized content
- G97: Expand each abbreviation at its first use
- G102: Explain every abbreviation where it first appears
- PDF8: Provide expansions for abbreviations in PDFs
Passes vs. fails
Passes
The same page says your Accessibility Conformance Report (ACR) should cite EN 301 549, the European standard. Both are spelled out on first use.
Fails
A page says your ACR should cite EN 301 549, and expands neither abbreviation anywhere.
In audits and lawsuits
This is Level AAA and it works more like a habit than a build task, since there is no component to install. One rule inside it is the part almost everybody gets wrong. Having become part of the language is the only exemption, and being common or familiar is not the same thing. Laser qualifies, because a dictionary now lists it as a word. NASA and IBM qualify, because they get used as names in their own right. HTML, PDF, FAQ and CEO do not, however familiar they feel. W3C gives a practical test for it. If a common dictionary lists the abbreviation as a word, you have reasonable grounds to claim the exemption.