1) off scouring, refuse
2a) the most abject and despicable men
2b) the price of expiation or redemption, because the Greeks used to apply the term "katharmata" to victims sacrificed to make expiation for the people, and even to criminals who were maintained at the public expense, that on the outbreak of a pestilence or other calamity they might be offered as sacrifices to make expiation for the state
Part of Speech: noun neuter
Citing in TDNT: 3:430, 381
From a compound of G4012 and G2508; something cleaned off all around, that is, refuse (figuratively): - filth.
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 περικάθαρμα; click on the second column to search for that grammatical form of the root περικάθαρμα; click on the third column to search for that word and grammatical form; click on the total to search for the root περικάθαρμα.