1) a cleansing, purification, a ritual purgation or washing
1a) of the washing of the Jews before and after their meals
1b) of levitical purification of women after childbirth
1c) a cleansing from the guilt of sins wrought by the expiatory sacrifice of Christ
Part of Speech: noun masculine
Citing in TDNT: 3:429, 381
From G2511; a washing off, that is, (ceremonially) ablution, (morally) expiation: - cleansing, + purge, purification, (-fying).
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 καθαρισμός; click on the second column to search for that grammatical form of the root καθαρισμός; click on the third column to search for that word and grammatical form; click on the total to search for the root καθαρισμός.