The force by which an object returns to its original shape after deformation; elasticity or rebound strength. Figuratively, it can mean the degree of resistance someone or something shows to pressure or interference.
ゴムボールは反発力が高いのでよく跳ねる。
Rubber balls bounce well because they have high rebound (elastic) force.
新素材は反発力に優れているため、衝撃吸収に適している。
The new material excels in elasticity, making it suitable for shock absorption.
彼の発言には反発力があって、上司の指示に従わないことが多い。
He has a contrarian streak and often resists his boss's instructions.