upsilon /ūp-sīˈlon, ŭp-, ūpˈsi- or upˈsi-/ or ypsilon /ip-sīˈlon or ipˈsi-/

1. The twentieth letter of the Greek alphabet (Υ, υ)
2. As a numeral υˈ = 400, ˌυ = 400000
3. A short-lived heavy subatomic particle produced when beryllium nuclei are bombarded with high-energy protons

• Guelfic
• Guelph
• guenon
• guenons
• guerdon
• guerdoned
• guerdoning
• guerdons
• guereza
• guerezas
• guerilla
• guerillas
• guernsey
• Guernsey lily
• guernseys
• guerre à mort
• guerre à outrance
• guerrilla
• guerrillas
• guerrillero
• guerrilleros
• gues
• guess
• guessable
• guessed