I've seen the side-to-side nod

Is there a word for the side-to-side 'nod', I wonder. It can't include the word "nod" because nod means to move one's head "up and down", not sideways.

"shaking" one's head comes close, but is "shaking" necessarily a side to side motion?

When you look at the definition of "nod" in A-H, "To lower and raise the head quickly", you can't help wondering if the words "north and south" are redundant. A nod is always north and south so a "north and south nod" is really no different than any other nod.

Perhaps it just sounds more intriguing -- which is apt, perhaps, because intrigue is what is suggested in the General's usage.