It's not specific nor limited to javascript. The term "canvas" in this context is much older and seems to be used across many platforms.

Random examples from the (desktop) Java/Android/iOS world where the same semantics is used:

https://docs.oracle.com/javase/8/docs/api/java/awt/Canvas.ht...

https://developer.android.com/reference/android/graphics/Can...

https://developer.apple.com/documentation/SwiftUI/Canvas

You may notice that the first reference is from java, and i bet js lifted it from there. They may have been aware of java because they lifted the name too.

The other two are too new to be relevant.

Flutter uses canvas when targeting the web. (At least it was the last time I looked at it years ago)

Canvas is the javascript name for writing directly to a frame buffer :)

There is a world outside the browser. For now.

Canvas predates javascript. For example, TCL's TK toolkit uses Canvas[1]

[1] https://tkdocs.com/tutorial/canvas.html