Noun
The twentieth letter of Classical and Modern Greek; the twenty-second letter of Old and Ancient Greek.
(physics) An upsilon meson, or bottomonium.
Source: en.wiktionary.orgAt Northwestern, he joined the Upsilon chapter of Phi Kappa Sigma and is listed among the more famous members of the fraternity. Source: Internet
Another method includes an asterism made up of Sigma, Chi, Tau, and Upsilon Octantis, which form a distinctive trapezoid shape. Source: Internet
In Libra, for example, the new designations sigma, tau, and upsilon were chosen to avoid conflict with Bayer's earlier designations, even though several stars with earlier letters are not as bright. Source: Internet
Epsilon Carinae and Upsilon Carinae are double stars visible in small telescopes. Source: Internet
Y was adopted to represent upsilon in loanwords from Greek, but it was pronounced like u and i by some speakers. Source: Internet