1) a vessel placed under a press (and in the Orient usually sunk in the earth) to receive the expressed juice of the grapes, a pit
Part of Speech: noun neuter
Citing in TDNT: 4:254, 531
Neuter of a presumed compound of G5259 and G3025; vessel or receptacle under the press, that is, lower winevat: - winefat.
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 ὑπολήνιον; click on the second column to search for that grammatical form of the root ὑπολήνιον; click on the third column to search for that word and grammatical form; click on the total to search for the root ὑπολήνιον.