1) want of strength, weakness, infirmity
1a) of the body
1a1) its native weakness and frailty
1a2) feebleness of health or sickness
1b) of the soul
1b1) want of strength and capacity requisite
1b1a) to understand a thing
1b1b) to do things great and glorious
1b1c) to restrain corrupt desires
1b1d) to bear trials and troubles
Part of Speech: noun feminine
Citing in TDNT: 1:490, 83
From G772; feebleness (of body or mind); by implication malady; moral frailty: - disease, infirmity, sickness, weakness.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root ἀσθένεια; click on the second column to search for that grammatical form of the root ἀσθένεια; click on the third column to search for that word and grammatical form; click on the total to search for the root ἀσθένεια.