Understanding Success Criterion 3.1.3: Unusual Words

Success Criterion 3.1.3 Unusual Words (Level AAA): A mechanism is available for identifying specific definitions of words or phrases used in an unusual or restricted way, including idioms and jargon.


Certain disabilities make it difficult to understand nonliteral word usage and specialized words or usage. Certain disabilities make it difficult to understand figurative language or specialized usage. Providing such mechanisms is vital for these audiences. Specialized information intended for non-specialist readers is encouraged to satisfy this Success Criterion, even when claiming only Single-A or Double-A conformance.


This Success Criterion may help people with cognitive, language and learning disabilities who:

It would also help people with visual disabilities who:


Related Resources

Resources are for information purposes only, no endorsement implied.


The inclusion of a product or vendor name in the list below does not constitute an endorsement by the Web Content Accessibility Guidelines Working Group or the Web Accessibility Initiative of the World Wide Web Consortium. This list is provided simply for convenience and to give users an idea of what resources may be available


Each numbered item in this section represents a technique or combination of techniques that the WCAG Working Group deems sufficient for meeting this Success Criterion. However, it is not necessary to use these particular techniques. For information on using other techniques, see Understanding Techniques for WCAG Success Criteria, particularly the "Other Techniques" section.

Sufficient Techniques

Select the situation below that matches your content. Each situation includes techniques or combinations of techniques that are known and documented to be sufficient for that situation.

Situation A: If the word or phrase has a unique meaning within the Web page:

  1. G101: Providing the definition of a word or phrase used in an unusual or restricted way for the first occurrence of the word or phrase in a Web page using one of the following techniques:

  2. G101: Providing the definition of a word or phrase used in an unusual or restricted way for each occurrence of the word or phrase in a Web page using one of the following techniques:

Situation B: If the word or phrase means different things within the same Web page:

  1. G101: Providing the definition of a word or phrase used in an unusual or restricted way for each occurrence of the word or phrase in a Web page using one of the following techniques:

Key Terms

assistive technology

hardware and/or software that acts as a user agent, or along with a mainstream user agent, to provide functionality to meet the requirements of users with disabilities that go beyond those offered by mainstream user agents


functionality provided by assistive technology includes alternative presentations (e.g., as synthesized speech or magnified content), alternative input methods (e.g., voice), additional navigation or orientation mechanisms, and content transformations (e.g., to make tables more accessible).


Assistive technologies often communicate data and messages with mainstream user agents by using and monitoring APIs.


The distinction between mainstream user agents and assistive technologies is not absolute. Many mainstream user agents provide some features to assist individuals with disabilities. The basic difference is that mainstream user agents target broad and diverse audiences that usually include people with and without disabilities. Assistive technologies target narrowly defined populations of users with specific disabilities. The assistance provided by an assistive technology is more specific and appropriate to the needs of its target users. The mainstream user agent may provide important functionality to assistive technologies like retrieving Web content from program objects or parsing markup into identifiable bundles.

Assistive technologies that are important in the context of this document include the following:

  • screen magnifiers, and other visual reading assistants, which are used by people with visual, perceptual and physical print disabilities to change text font, size, spacing, color, synchronization with speech, etc. in order to improve the visual readability of rendered text and images;
  • screen readers, which are used by people who are blind to read textual information through synthesized speech or braille;
  • text-to-speech software, which is used by some people with cognitive, language, and learning disabilities to convert text into synthetic speech;
  • speech recognition software, which may be used by people who have some physical disabilities;
  • alternative keyboards, which are used by people with certain physical disabilities to simulate the keyboard (including alternate keyboards that use head pointers, single switches, sip/puff and other special input devices.);
  • alternative pointing devices, which are used by people with certain physical disabilities to simulate mouse pointing and button activations.

satisfying all the requirements of a given standard, guideline or specification


phrase whose meaning cannot be deduced from the meaning of the individual words and the specific words cannot be changed without losing the meaning


idioms cannot be translated directly, word for word, without losing their (cultural or language-dependent) meaning.

In English, "spilling the beans" means "revealing a secret." However, "knocking over the beans" or "spilling the vegetables" does not mean the same thing.

In Japanese, the phrase "さじを投げる" literally translates into "he throws a spoon," but it means that there is nothing he can do and finally he gives up.

In Dutch, "Hij ging met de kippen op stok" literally translates into "He went to roost with the chickens," but it means that he went to bed early.


words used in a particular way by people in a particular field

The word StickyKeys is jargon from the field of assistive technology/accessibility.


process or technique for achieving a result


The mechanism may be explicitly provided in the content, or may be relied upon to be provided by either the platform or by user agents, including assistive technologies.


The mechanism needs to meet all success criteria for the conformance level claimed.


series of user actions where each action is required in order to complete an activity

Successful use of a series of Web pages on a shopping site requires users to view alternative products, prices and offers, select products, submit an order, provide shipping information and provide payment information.

An account registration page requires successful completion of a Turing test before the registration form can be accessed.

relied upon

the content would not conform if that technology is turned off or is not supported


mechanism for encoding instructions to be rendered, played or executed by user agents


As used in these guidelines "Web Technology" and the word "technology" (when used alone) both refer to Web Content Technologies.


Web content technologies may include markup languages, data formats, or programming languages that authors may use alone or in combination to create end-user experiences that range from static Web pages to synchronized media presentations to dynamic Web applications.

Some common examples of Web content technologies include HTML, CSS, SVG, PNG, PDF, Flash, and JavaScript.

used in an unusual or restricted way

words used in such a way that requires users to know exactly which definition to apply in order to understand the content correctly

The term "gig" means something different if it occurs in a discussion of music concerts than it does in article about computer hard drive space, but the appropriate definition can be determined from context. By contrast, the word "text" is used in a very specific way in WCAG 2.1, so a definition is supplied in the glossary.

user agent

any software that retrieves and presents Web content for users

Web browsers, media players, plug-ins, and other programs — including assistive technologies — that help in retrieving, rendering, and interacting with Web content.