1. One who ventures into unknown or unclaimed territory to settle. 2. a pioneer in aviation. 3. A soldier who performs construction and demolition work in the field to facilitate troop movements. 4. An animal or plant species that establishes itself in a previously barren environment. 5. the pioneer spirit. 6. a pioneer treatment for cancer. 7. rockets that pioneered outer space. 8. To settle (a region). 9. surgeons who pioneered organ transplants. 10. pioneered in development of the laser.
