1) a wing, a little wing
2) any pointed extremity
2a) of fins of fishes
2b) of part of a dress hanging down in the form of a wing
2c) of the top of the temple at Jerusalem
Part of Speech: noun neuter
Neuter of a presumed derivative of G4420; a winglet, that is, (figuratively) extremity (top corner): - pinnacle.
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 πτερύγιον; click on the second column to search for that grammatical form of the root πτερύγιον; click on the third column to search for that word and grammatical form; click on the total to search for the root πτερύγιον.