How do you spell Preemption

Available Definitions:
1)  n. - The act or right of purchasing before others.
2)  n. - The privilege or prerogative formerly enjoyed by the king of buying provisions for his household in preference to others.
3)  n. - The right of an actual settler upon public lands (particularly those of the United States) to purchase a certain portion at a fixed price in preference to all other applicants.