---
title: "@stillwind-undef-utility"
description: "Remove built-in or plugin utility definitions that match a name or a prefix."
image: "https://stillwind.dev/og.png"
---

> Documentation Index
> Fetch the complete documentation index at: https://stillwind.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# @stillwind-undef-utility

```css
@stillwind-undef-utility name;
@stillwind-undef-utility prefix-*;
@stillwind-undef-utility *;
```

`@stillwind-undef-utility` removes the matching utility definitions that
register before it. A removed utility becomes unknown, and
[unknown-utility](/docs/lints/unknown-utility) reports its uses. Write it at the
top level of the stylesheet or in a
[@stillwind-registry](/docs/at-rules/stillwind-registry) block.

## Example

### Stylesheet

```css
@stillwind-undef-utility float-*;

@utility float-start {
  float: inline-start;
}
```

### Source

```tsx
import { style } from "stillwind/react";

export const removed = style("float-left");
export const replaced = style("float-start");
```

### Compiled code

```ts
export const removed = {};
export const replaced = {className:"sw_vofby"};
```

### Generated stylesheet without preflight

```css
/*! stillwind v0.0.0 | MIT License | https://stillwind.dev */
/*! tailwindcss v4.3.3 | MIT License | https://tailwindcss.com */
@layer properties, theme, base, components, utilities;

@layer utilities {
  .sw_vofby {
    float: inline-start;
  }
}
```

The statement removes every built-in `float-*` utility. `float-left` produces no
class, and `float-start` uses only the new definition.

## Patterns

A pattern is `*`, an exact name, or a prefix followed by `*`. `duration-*`
matches the definition `duration-*` and the exact names that start with
`duration-`, such as `duration-initial`. It does not match `-duration-*`: a
pattern for negative names starts with `-`.

## Order

The statements that `@plugin` generates register first. The other statements,
including the built-in definitions that `@import "stillwind"` loads, follow in
source order. An undefinition removes only definitions that register before it:

- It removes plugin utilities, wherever the `@plugin` statement stands.
- It removes the built-in utilities that `@import "stillwind"` loads before it.
- It does not remove a `@utility` that comes after it, so you can remove a
  built-in utility and define your own utility with the same name.

A replacement with the same name keeps the cascade position of the removed
definition, so it wins against the same utilities as before. A definition with
another name takes the position where you write it. A definition without `*`
does not take the position of a removed `prefix-*` definition.
The [logical stylesheets](/docs/concepts/stylesheets#logical-axis-utilities) replace
utilities in this way.

Outside a block, the statement changes the `default`, `keyframe`, and
`view-transition` registries.

To report uses of a utility without removing it, use
[no-restricted-utilities](/docs/lints/no-restricted-utilities) instead.

Source: https://stillwind.dev/docs/at-rules/stillwind-undef-utility/index.mdx