1) a veil spread out, a curtain
1a) the name given to the two curtains in the temple at Jerusalem, one of them at the entrance to the temple separated the Holy Place from the outer court, the other veiled the Holy of Holies from the Holy Place
Part of Speech: noun neuter
Citing in TDNT: 3:628, 420
From a compound of G2596 and a congener of G4072; something spread thoroughly, that is, (specifically) the door screen (to the Most Holy Place) in the Jewish Temple: - vail.
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 καταπέτασμα; click on the second column to search for that grammatical form of the root καταπέτασμα; click on the third column to search for that word and grammatical form; click on the total to search for the root καταπέτασμα.