Their resilience was tested by the long illness, but they never lost hope.

resilience 是名词，来自形容词 resilient（有弹性的、能复原的）。词根是拉丁语 resilire（跳回、反弹），由 re-（回）和 salire（跳）组成。resilience 指"从困境中恢复的能力"或"适应力、韧性"。