Functiona11ity Error

A term coined by Zhong et al. (2026) — a portmanteau of 'functionality' and 'a11y' (accessibility) — for an accessibility barrier that only manifests through interaction. The static state of the UI appears accessible (elements have labels, sufficient contrast, correct roles), but the dynamic behaviour fails to meet user expectations or WCAG criteria: a button's action produces no feedback, a label does not match what the control actually does, focus gets trapped, or an input field cannot be activated. Because functiona11ity errors depend on the outcome of an action rather than a property of a single element, they are missed by most static accessibility checkers and require runtime task execution (ideally through a screen reader) to detect.