noun

the state of being decrepit.

he had passed directly from middle age into decrepitude

feebleness,enfeeblement,infirmity,weakness,frailty,debilitation,debility,sickliness,incapacitation,malaise,old age,agedness,elderliness,dotage,senility,superannuation,senescence,dilapidation,ricketiness,dereliction,ruin,disrepair,rack and ruin,decay,deterioration