noun · neuterȳpsīlonYPSILONȳpsīlon n (indeclinable)Classical[yːpˈsiː.ɫɔn]Ecclesiastical[ipˈsiː.lon]☆ KeepMeaningindeclinableA name of the letter Y.OriginsBorrowed from Koine Greek ὖ ψιλόν (û psilón).