1) the fist, clenched hand
2) up to the elbow
Part of Speech: noun feminine
Citing in TDNT: 6:915, 973
From a primary word, πύζ pux, (the fist as a weapon); the clenched hand, that is, (only in the dative case as adverb) with the fist (hard scrubbing): - oft.
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 πυγμή; click on the second column to search for that grammatical form of the root πυγμή; click on the third column to search for that word and grammatical form; click on the total to search for the root πυγμή.