Overlays & Surfaces · Containers
Expander
also known as expand/collapse, twisty
An expander is a toggle that grows to show additional content and shrinks to hide it, typically shown with a chevron or plus/minus icon. It's functionally the same as a disclosure and often used for tree nodes, settings groups, or 'read more' regions. The name is common in Microsoft's and other component libraries.
See it live — shadcn/ui · MUI · Ant Design
Don't confuse it with
Expander, disclosure, and collapsible describe the same single show/hide behavior under different names. It differs from an accordion, which is a coordinated group of these sections rather than one standalone toggle.
In the wild
The chevron that expands a subfolder in a file-tree sidebar acts as an expander.