Why .Net Lambda expressions are called “Lambda expressions”

I never asked myself what are the origins of the .Net “Lambda expressions” name, but several days ago I was searching some info about quantum programming and as usual I ended by reading total different article which was Lambda calculus which presents a mathematical concept/theory from 1937 used for expressing computation based on function abstraction and application. In that article I discovered concepts of anonymous functions and of course a very familiar notation of it x -> 2+x which is equivalent with f(x)=2+x, looks familiar?