1) a deposit, a trust or thing consigned to one's faithful keeping
1a) used of the correct knowledge and pure doctrine of the gospel, to be held firmly and faithfully, and to be conscientiously delivered unto others
Part of Speech: noun feminine
Citing in TDNT: 8:162, 1176
From a compound of G3844 and G2698; something put down alongside, that is, a deposit (sacred trust): - that (thing) which is committed (un-) to (trust).
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 παρακαταθήκη; click on the second column to search for that grammatical form of the root παρακαταθήκη; click on the third column to search for that word and grammatical form; click on the total to search for the root παρακαταθήκη.