3.1.3: Unusual Words

What it means

Provide definitions for unusual words, idioms, and jargon used in content — unless they are defined in context or are proper names. AAA readability helps cognitive disabilities and new readers.

Define terms the first time you use them on a site.

How to fix it

• Link jargon to a glossary entry the first time it appears.
• Explain idioms in plain language nearby.
• Offer a site glossary for industry-specific terms.
• Use definition lists or abbr with title for abbreviations that are not expanded.

Quick examples

• Good: The first use of “WCAG” links to a glossary definition.
• Bad: Legal pages use Latin terms with no explanation.
• Good: An idiom is followed by a plain-language restatement.
• Bad: Medical acronyms appear throughout with no expansion or glossary.