the
filename extension used to denote
emacs lisp files. (like "
foo.el", or whatever)
sort of a funny(?) pun, if you are a geek; "el" could be pronounced "E L", as in "Emacs Lisp", or just "ell", which sounds exactly like "L", which is the extension used to denote Common Lisp files.
(actually, I just made that last bit up; please don't hurt me!)