1) once, i.e. formerly, aforetime, at some time
Part of Speech: particle
From the base of G4225 and G5037; indefinite adverb, at some time, ever: - afore- (any, some-) time (-s), at length (the last), (+ n-) ever, in the old time, in time past, once, when.
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 πότε; click on the second column to search for that grammatical form of the root πότε; click on the third column to search for that word and grammatical form; click on the total to search for the root πότε.