1. ex- "away from" + propri- "one's own, particular to itself" + -ate.
2. => take away from one's own property, deprive of one's own property.
3. => a taking of someone's property, especially for public use.
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.