confederation

Short definition from Wiktionary

Noun

1. 1
   A union or alliance of states or political organizations.
2. 2
   The act of forming an alliance.

Proper noun

1. 1
   In Canada, the federal union of provinces and territories which formed Canada, beginning with New Brunswick, Nova Scotia, Ontario, and Quebec, and later including all the others.
2. 2
   In Canada, the federal union of provinces and territories which formed Canada, beginning with New Brunswick, Nova Scotia, Ontario, and Quebec, and later including all the others: In Canada, the date of Confederation; 1 July 1867.
3. 3
   In Newfoundland, the political union of Newfoundland with Canada.
4. 4
   In Newfoundland, the political union of Newfoundland with Canada: In Newfoundland, the date of Confederation; 31 March 1949.