Former political organization in the Canadian province of Quebec that advocated Quebec becoming the 51st state of the United States. They thought that it might be possible to arrange for Quebec to have only one official language more easily than if they remained part of Canada. This was probably true, except that the one official language wouldn't have been Français. The organization's policies don't appear to have been well thought-out.
Mouvement 51 wanted to ensure a French-speaking Quebec by becoming part of the United States. C'est fou!