1. A gradual decrease or deterioration in one's physical, mental, or functional capabilities
The patient experienced a decline in ability to walk after the surgery.
O paciente experimentou um declínio na capacidade de caminhar após a cirurgia.
2. Loss of skill, strength, or competence over time
There was a noticeable decline in ability in her chess performance.
Houve um declínio notável na capacidade de desempenho no xadrez dela.