upsilon upsiloid • upsilonism · · · Info · Definitions · Characters · · upsilon · · Text Latin · · Script 7 · · Length 3 · · Syllables Definitions · · · (noun) the 20th letter of the Greek alphabet. · · Noun Definition 1 Characters · · i latin small letter i U+0069 l latin small letter l U+006C n latin small letter n U+006E o latin small letter o U+006F p latin small letter p U+0070 s latin small letter s U+0073 u latin small letter u U+0075