If you have somehow managed to find this site, you are either curious
about the name xlerb, or you already know what it means. If you already
know what it means, then there’s probably not much point in reading
further.
xlerb is a “word that doesn’t exist in the dictionary.” It was coined by
Leo Brodie in the seminal programming tome
Starting Forth.
Forth, if you’re not aware, is made up of “words” that decompose into
smaller words, which ultimately end up written in assembler.
Forth maintains a dictionary of words, and scans it for each word in
its input stream.
xlerb is not a word.
So now you know the rest of the story.