debility /dɪˈbɪlɪtɪ/

• 1. 

  N-VAR Debility is a weakness of a person's body or mind, especially one caused by an illness. (尤指疾病引起的身体或神志)衰弱 [正式]

  例：

  ...exhaustion or post-viral debility.

  ... 劳累或病毒感染后所致的体弱。