1) the season which succeeds summer, from the rising of Sirius to that of Arcturus, i.e. from late summer, early autumn, our dog days
2) ripe fruits (of trees)
Part of Speech: noun feminine
Apparently from the base of G3796 and G5610; properly even tide of the (summer) season (dog days), that is, (by implication) ripe fruit: - fruit.
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 ὀπώρα; click on the second column to search for that grammatical form of the root ὀπώρα; click on the third column to search for that word and grammatical form; click on the total to search for the root ὀπώρα.