1) to uncover, lay open what has been veiled or covered up
1a) disclose, make bare
2) to make known, make manifest, disclose what before was unknown
Part of Speech: verb
Citing in TDNT: 3:563, 405
From G575 and G2572; to take off the cover, that is, disclose: - reveal.
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 ἀποκαλύπτω; click on the second column to search for that grammatical form of the root ἀποκαλύπτω; click on the third column to search for that word and grammatical form; click on the total to search for the root ἀποκαλύπτω.