diff --git a/acorn/README.md b/acorn/README.md
index cfc51b384..f7ff96624 100644
--- a/acorn/README.md
+++ b/acorn/README.md
@@ -50,12 +50,11 @@ Options are provided by in a second argument, which should be an
 object containing any of these fields (only `ecmaVersion` is
 required):
 
-- **ecmaVersion**: Indicates the ECMAScript version to parse. Must be
-  either 3, 5, 6 (or 2015), 7 (2016), 8 (2017), 9 (2018), 10 (2019),
-  11 (2020), 12 (2021), 13 (2022), 14 (2023), or `"latest"` (the
-  latest the library supports). This influences support for strict
-  mode, the set of reserved words, and support for new syntax
-  features.
+- **ecmaVersion**: Indicates the ECMAScript version to parse. Can be a
+  number, either in year (`2022`) or plain version number (`6`) form,
+  or `"latest"` (the latest the library supports). This influences
+  support for strict mode, the set of reserved words, and support for
+  new syntax features.
 
   **NOTE**: Only 'stage 4' (finalized) ECMAScript features are being
   implemented by Acorn. Other proposed new features must be
diff --git a/acorn/src/acorn.d.ts b/acorn/src/acorn.d.ts
index cf72b3704..71b37916e 100644
--- a/acorn/src/acorn.d.ts
+++ b/acorn/src/acorn.d.ts
@@ -573,16 +573,15 @@ export function tokenizer(input: string, options: Options): {
   [Symbol.iterator](): Iterator<Token>
 }
 
-export type ecmaVersion = 3 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | "latest"
+export type ecmaVersion = 3 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | "latest"
 
 export interface Options {
   /**
-   * `ecmaVersion` indicates the ECMAScript version to parse. Must be
-   * either 3, 5, 6 (or 2015), 7 (2016), 8 (2017), 9 (2018), 10
-   * (2019), 11 (2020), 12 (2021), 13 (2022), 14 (2023), or `"latest"`
-   * (the latest version the library supports). This influences
-   * support for strict mode, the set of reserved words, and support
-   * for new syntax features.
+   * `ecmaVersion` indicates the ECMAScript version to parse. Can be a
+   * number, either in year (`2022`) or plain version number (`6`) form,
+   * or `"latest"` (the latest the library supports). This influences
+   * support for strict mode, the set of reserved words, and support for
+   * new syntax features.
    */
   ecmaVersion: ecmaVersion