The Constitution Act, 1867 used the status term “Dominion” for Canada, inspiring the old holiday name Dominion Day.
Section 3 authorized the union of Canada, Nova Scotia, and New Brunswick as “one Dominion under the Name of Canada.” The term described a self-governing country within the British Empire, rather than a kingdom or a republic. Canada’s first national holiday was commonly called Dominion Day before being renamed Canada Day in 1982.
The word’s adoption is often linked to Psalm 72:8, whose “dominion … from sea to sea” wording appealed to Confederation leaders. It also suited the ambition of creating a country stretching from the Atlantic toward the Pacific.
A technical detail commonly missed is that the Constitution Act’s exact wording is “one Dominion under the Name of Canada,” not necessarily the standalone formal phrase “Dominion of Canada” in every constitutional provision. Nevertheless, Dominion became the enduring historical description of the new federation.