Why is the ninth month called September?
mid-15c., "renunciation of worldly goods," from Medieval Latin expropriationem (nominative expropriatio), noun of action from Late Latin expropriare "deprive of property," from ex- "away from" (see ex-) + propriare "to appropriate" (see appropriate). Sense of "a taking of someone's property," especially for public use, is from 1848; as Weekley puts it, "Current sense of organized theft appears to have arisen among Ger. socialists."
1610s, back-formation from expropriation, or from earlier adjective (mid-15c.), or from Medieval Latin expropriatus, past participle of expropriare "to deprive of one's own." Related: Expropriated; expropriating.
The taking over of private property by a government, often without fair compensation but usually with a legal assertion that the government has a right to do so.