1. The power to repel: In the story, the giant possessed enough repellant and force to fend off anything in his way.
2. A chemical substance that fend off animals: Mary had an insect repellant especially to keep off the mosquitoes while camping in the woods.
3. A compound with which fabrics are treated to wards off moisture: The raincoat that Sam bought contained a repellant to withstand any rain or water.