Double Negative

Hi,
I have looked through sooo many books and all over the internet to see if there is a word to describe a double negative. I was complaining loudly on a bus the other day and a man told me that the word was 'Litotes', however this is a slightly different definition.
Do you know if there is a single word to describe a double negative, and if there is, what is it?!

Many many thanks

[MrPedantic]

Hello Unreg

"Double negative" describes the phenomenon; "litotes" describes a particular rhetorical use of the phenomenon, whereby the speaker affirms X by denying X's negation, e.g.

1. He was not unhappy.
2. The attempt was not unsuccessful.
3. I will in no way deny that negation.

Other members may have other thoughts, though, so keep watching!

All the best,

MrP