That's not at all what a runtime is, in any context, ever. Where else have you seen this solecism? It's new to me.

First sentence of the Wikipedia article for Node.js:

> Node.js is a cross-platform, open-source JavaScript runtime environment that can run on Windows, Linux, Unix, macOS, and more.

First sentence for the Wikipedia article Deno:

> Deno is a runtime for JavaScript, TypeScript, and WebAssembly that is based on the V8 JavaScript engine and the Rust programming language.

First line of hero text from Node.js's site:

> Node.js® is a free, open-source, cross-platform JavaScript runtime environment that lets developers create servers, web apps, command line tools and scripts.

First line of hero text from Deno's site:

> Deno is the open-source JavaScript runtime for the modern web.

> Where else have you seen this

Node.js is easily the most famous example. Also deno, bun, winterjs, and probably a bunch more.

Someone upthread just linked a bunch of other equivalent lua projects that also refer to themselves as runtimes: https://news.ycombinator.com/item?id=46036362

I've also seen discussions where wrapping the servo-browser-engine in a UI layer referred to the UI layer as a runtime, though I think that's a substantially less canonical use of the word than referring to the part of an implementation that takes requests from the interpreter and executes them in the surrounding environment as a runtime.