Dominion vs Mainland

Dominion

name

  • Any of the self-governing nations of the British Commonwealth until 1949. 

Mainland

name

  • A historical region in British Columbia, British North America, British Empire 

  • The largest island in the Orkney Islands council area, to the north of Scotland. 

  • The largest island in the Shetland Islands council area, to the north of both Orkney and Scotland. 

How often have the words Dominion and Mainland occurred in a corpus of books? (source: Google Ngram Viewer )