lessen

The pain will lessen [=decrease] over time.过段时间疼痛就会减轻。

Medication helps lessen the severity of the symptoms.药物治疗有助于减轻症状。

Taking a few simple precautions will lessen [=(more commonly) reduce] your risk of injury.采取一些简单的预防措施将会减少你受伤的风险。