imperialise

/IH1 M P IH1 R IY0 AH0 L AH0 S/
verb
  1. 1

    To invest with imperial authority, character, or style.

  2. 2

    To bring to the form of an empire.

    โ€œThe competition to imperialize foreign lands was another cause of World War I.โ€

Source: https://en.wiktionary.org/wiki/imperialise, https://en.wiktionary.org/wiki/imperialize