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 (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).]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(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]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(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]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
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"
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
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.
From species to species, as: 'With blade of bronze drew away the life,' and 'Cleft the water with the vessel of unyielding bronze.' 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.'
Logan College's Upsilon Pi Chapter had nominated Barkley Giffin for the Distinguished Adviser Award.
Prospero De Vera urged members of the Upsilon Sigma Phi fraternity, especially those occupying top positions in the government, to speak and act on the controversial online conversation hit for its misogynist, sexist, and violent messages.
UP president: No protection for fraternity brother culpable in #LonsiLeaks !-- -- ( - November 23, 2018 - 2:37pm MANILA, Philippines University of the Philippines president and Upsilon Sigma Phi member Danilo Concepcion on Friday denounced the leaked conversations linked to his fraternity and vowed thorough investigation into the matter.
Aside from the recent brawl involving members of two fraternities, he also finds a series of offensive posts on social media attributed to the Upsilon Sigma Phi "more disturbing."
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 3.00 Newbury The story Pauline Robson describes herself as a hands-on trainer who, after riding out yesterday, was behind the steering wheel of her horsebox transporting Upsilon Bleu on the five-hour-plus trip south from her Northumberland base to Newbury.
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.