debility

Etymology

From Middle English debylite, from Old French debilité (French débilité), from Latin dēbilitās (“weakness”), from dēbilis (“weak”), from dē- + habilis (“able”).

noun

1. A state of physical or mental weakness.
   I was ready to sink from fatigue and hunger, but being surrounded by a crowd, I thought it politic to rouse all my strength, that no physical debility might be construed into apprehension or conscious guilt. […]
   I was struck besides with the shocking expression of his face, with his remarkable combination of great muscular activity and great apparent debility of constitution 1886, Robert Louis Stephenson, The Strange Case of Dr Jekyll and Mr Hyde