Also found in: Thesaurus, Medical, Financial, Encyclopedia, Wikipedia.


 (ŭp′sə-lŏn′, yo͞op′-)
The 20th letter of the Greek alphabet. See Table at alphabet.

[Late Greek ū psīlon, simple u (from the fact that oi was given the same pronunciation in Late Greek as u) : ū, hū, the letter U + psīlon, neuter of psīlos, simple (written with one letter as opposed to two).]


(ˈʌpsɪˌlɒn; juːpˈsaɪlən)
(Letters of the Alphabet (Foreign)) the 20th letter in the Greek alphabet (Υ, υ), a vowel, transliterated as y or u
[C17: from Medieval Greek u psilon simple u, name adopted for graphic u to avoid confusion with graphic oi, since pronunciation was the same for both in Late Greek]


(ˈyup səˌlɒn, -lən, ˈʌp-; esp. Brit. yupˈsaɪ lən)

1. the 20th letter of the Greek alphabet (Y, υ).
2. Also called up′silon par`ticle. any of a family of heavy, short-lived, neutral mesons that are composed of a bottom quark and its antiquark. Symbol:Y, υ
[1615–25; < Late Greek ŷ psīlón literally, simple u (to distinguish it from the diagraph oi, pronounced the same in Late Greek]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.upsilon - the 20th letter of the Greek alphabetupsilon - the 20th letter of the Greek alphabet
Greek alphabet - the alphabet used by ancient Greeks
alphabetic character, letter of the alphabet, letter - the conventional characters of the alphabet used to represent speech; "his grandmother taught him his letters"
References in classic literature ?
The word {sigma iota gamma upsilon nu omicron nu}, 'lance,' is to the Cyprians a current term but to us a strange one.
Here {alpha rho upsilon rho alpha iota}, 'to draw away,' is used for {tau alpha mu epsilon iota nu}, 'to cleave,' and {tau alpha mu epsilon iota nu} again for {alpha rho upsilon alpha iota},--each being a species of taking away.
epsilon rho nu upsilon gamma epsilon sigma}, 'sprouters,' for {kappa epsilon rho alpha tau alpha}, 'horns,' and {alpha rho eta tau eta rho},
supplicator,' for {iota epsilon rho epsilon upsilon sigma}, 'priest.
The Upsilon Sigma Phi will kick off its 100th anniversary on Friday with a rock and jazz concert for all fellows.
One of the black students, who was&nbsp;in front of the Delta Upsilon fraternity house at the time of the incident, informed other legion members.
alpha beta gamma delta epsilon eta zeta theta iota kappa lambda mu nu xi omicron pi rho sigma tau upsilon phi chi psi omega.
MY BIG DAY PAULINE ROBSON The horse Upsilon Bleu The race 3.
He has landed the top prize twice in recent years with Merigo and -- while he's not represented in the big 'un today -- the proud Scot could still be on the winning podium earlier on the card with UPSILON BLEU.
From there, jump north 6 1/2[degrees] to 5th-magnitude Upsilon ([upsilon]) Aquarii.
RenaissanceRe has declared about the formation of Upsilon Reinsurance II Ltd, a new Bermuda-domiciled special purpose insurance vehicle, which will create extra reinsurance capacity for the global retrocessional reinsurance market.
M2 EQUITYBITES-January 4, 2013-RenaissanceRe forms new Bermuda domiciled special purpose insurance vehicle Upsilon Re II(C)2013 M2 COMMUNICATIONS http://www.