Is Javascript runtime environment a program?

I’ve been trying to understand what a runtime environment really means after I searched what Node js is

Node.js® is a JavaScript runtime built on Chrome’s V8 JavaScript engine.

I get that Node js uses V8 as its Javascript engine which can read Js Code, interpret it and run it, and that the runtime environment provides extra functionalities to your Javascript.

but if someone asks me what a runtime environment is, should I say it is a program which has two main jobs:

• to use a JS engine to read JS code and run it
• to provide extra functionalities to Javascript

if it is not a program, what should I call it?