Linguistic meaning of 'let' variable in programming [duplicate]

So, I'm a javascript programmer and the new version of JavaScript (ES6) has a new keyword for declaring variables: let, next to the old one var.

I know the difference between these two, but I was asking myself: what does let stand for? var obviously is an abbreviation of "variable", but let? Is it an abbreviation as well? Where does it come from?

I googled this and to my amazement, I couldn't find an answer. I already knew Swift also has a let keyword (they use it for constants), but apparently some other programming languages use it as well.

It comes from the English word 'let'.

verb: "let", "letting". 1. to allow or permit:

// Hey computer, can you please
let 
// this
night = 'wonderful'

Lisp has the keyword let and it's been around since 1958, though it may have come from even earlier.