In the entry for です,
http://jisho.org/words?jap=desu&eng=&dict=edict
the verb is labeled as "Common word, Auxillary, Polite language".
But I believe the correct spelling is "auxiliary" (only one "l").
I know this is nit-picking, but this is a dictionary....
You are correct: http://oxforddictionaries.com/definition/auxiliary?q=AUXILIARY
"Spelling help
There is only one l in auxiliary."
It looks like you're new here. If you want to get involved, click one of these buttons!