Goal
Help users understand unusual or specialized words.
Success Criterion · WCAG 3.1.3
Unusual Words
A mechanism is available for identifying specific definitions of words or phrases used in an unusual or restricted way, including idioms and jargon.
Level AAAWCAG 2.0Understandable3.1 · Readable
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What to do
Provide definitions or explanations for unusual words, jargon, idioms, or terms used in a non-standard way.
Why it matters
Unusual words can be a barrier for users with cognitive disabilities, non-native speakers, and newcomers to a domain.
Success criterion
What WCAG 3.1.3 requires
Summarized directly from the official Understanding document so teams can quote the requirement accurately.
A mechanism is available for identifying specific definitions of words or phrases used in an unusual or restricted way, including idioms and jargon.
Intent
Why WCAG created this requirement
- Definitions reduce comprehension barriers for specialized vocabulary.
- Idioms and jargon are particularly difficult for non-native speakers.
- A “mechanism” can be a glossary, expandable definition, or contextual help.
Benefits
Who gains when you pass
- Users with cognitive disabilities can understand content without guessing.
- Non-native speakers can interpret idioms and jargon.
- New users can learn domain terms (e.g., “VPAT,” “CART,” “ARIA”).
Why it matters
User impact when this criterion fails
Summaries drawn from the Understanding document help you socialize impact statements with product stakeholders.
Users may misunderstand critical instructions due to unfamiliar terminology.
Users may abandon content that feels opaque or overly technical.
Overview
When you use jargon, idioms, or words with special meanings, provide a way for users to learn what they mean (inline definitions, glossary, tooltips, or links).
- Provide definitions at first use, or link to a glossary.
- Ensure definition mechanisms are accessible (keyboard, screen reader).
- Avoid relying on hover-only tooltips for definitions (see 1.4.13).
Reference: All summaries and highlights originate from Understanding WCAG 3.1.3 and the W3C quick reference.
Fast facts
- Conformance level
- Level AAA
- WCAG version introduced
- WCAG 2.0
- Principle
- Understandable
- Guideline
- 3.1 · Readable
Examples
Make success tangible for teams
Share pass/fail snapshots to coach designers, engineers, QA, and content authors.
Jargon
Pass
“Use <abbr title="Accessible Rich Internet Applications">ARIA</abbr> attributes…”
Fail
“Use ARIA to implement semantics” with no explanation anywhere.
Idiom
Pass
“Avoid ‘hit the ground running’ (meaning: start quickly)…”
Fail
Idioms used heavily with no explanation.
Evidence to keep
Document conformance decisions
Capture artifacts for VPATs, procurement reviews, and regression testing.
- Maintain a glossary of common terms and acronyms used across the site.
- Document a content rule: define jargon at first use.
Official resources
Deep dives and supporting material
Keep these links handy when writing acceptance criteria or responding to audits.
Implementation checklist
Capture progress and blockers
- Identify jargon/idioms and restricted-use terms in content.
- Provide a glossary page or inline definitions for key terms.
- Link acronyms to definitions on first use.
- Ensure tooltips/definitions are keyboard accessible and persistent as needed.
Testing ideas
Prove conformance with evidence
- Scan content for terms likely to be unfamiliar.
- Verify a definition mechanism exists and is reachable by keyboard.
- Use a screen reader to confirm definition content is announced/accessible.
Related success criteria