1807, "to deprive of nationality, remove or destroy the distinct nationality of," from French dénationaliser, which was said in contemporary English publications to have been coined by Napoleon Bonaparte in reference to the nations he had conquered and absorbed into France (denapoleonize was coined shortly thereafter); see de- + nationalize. Meaning "to transfer (an industry, etc.) from national to private ownership" is by 1921. Related: Denationalized; denationalization.
updated on July 19, 2018