1) mercy: kindness or good will towards the miserable and the afflicted, joined with a desire to help them
1a) of men towards men: to exercise the virtue of mercy, show one's self merciful
1b) of God towards men: in general providence; the mercy and clemency of God in providing and offering to men salvation by Christ
1c) the mercy of Christ, whereby at his return to judgment he will bless true Christians with eternal life
Part of Speech: noun neuter
Citing in TDNT: 2:477, 222
Of uncertain affinity; compassion (human or divine, especially active): - (+ tender) mercy.
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 ἔλεος; click on the second column to search for that grammatical form of the root ἔλεος; click on the third column to search for that word and grammatical form; click on the total to search for the root ἔλεος.