WCAG 2.1 SC 3.1.3: Unusual Words (Level AAA)
3.1.3 Unusual Words (Level AAA) — what it requires, a common failure example, and how to fix it. Part of WCAG 2.1's 3.1 Readable guideline under the Understandable principle.
WCAG 2.1 guidelines hub → Understandable → 3.1 Readable
3.1.3 Unusual Words (Level AAA)
Readable is about making the language of your content programmatically identifiable, so screen readers pronounce it correctly and translation/reading tools work as intended. Most sites clear the Level A bar here with a single HTML attribute; the AAA criteria go further, into content clarity, that most sites won’t target.
This page is educational technical reference material, not legal advice. Meeting WCAG 2.1 does not by itself determine legal compliance with the ADA or any other law — consult qualified counsel for legal risk questions.
Plain-language explanation: If content uses jargon, idioms, or words in a specialized or unusual sense, there should be a way to look up what’s meant — a glossary link, an inline definition, or similar.
Common failure: A technical spec sheet uses industry jargon (“denier,” “GSM,” “thread count”) with no definitions anywhere on the page or site, leaving readers unfamiliar with the terms to guess.
Remediation: Link unusual terms to a glossary page or provide inline definitions (e.g. via a <dfn> element or an expandable tooltip that’s also keyboard- and screen-reader-accessible).
In this guideline — 3.1 Readable: 3.1.1 Language of Page (A) · 3.1.2 Language of Parts (AA) · 3.1.3 Unusual Words (AAA) · 3.1.4 Abbreviations (AAA) · 3.1.5 Reading Level (AAA) · 3.1.6 Pronunciation (AAA)
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This page is educational content about technical accessibility practice, not legal advice. Meeting WCAG 2.1 does not guarantee legal compliance with the ADA or any other law. Consult qualified counsel for legal risk questions.
This page was drafted with AI assistance and reviewed by a person for accuracy before publication.