upsilon

[ yoop-suh-lon, -luh n, uhp-; especially British yoop-sahy-luh n ]
/ ˈyup səˌlɒn, -lən, ˈʌp-; especially British yupˈsaɪ lən /

noun

the 20th letter of the Greek alphabet (Υ, υ).
the vowel sound represented by this letter.
Also called upsilon particle. Physics. any of a family of heavy, short-lived, neutral mesons that are composed of a bottom quark and its antiquark. Symbol: Υ, υ

Origin of upsilon

1615–25; < Late Greek ŷ psīlón literally, simple u (to distinguish it from the digraph oi, pronounced the same in LGk)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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British Dictionary definitions for upsilon

upsilon

/ (ˈʌpsɪˌlɒn, juːpˈsaɪlən) /

noun

the 20th letter in the Greek alphabet (Υ, υ), a vowel, transliterated as y or u

Word Origin for upsilon

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 & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for upsilon

upsilon


n.

The 20th letter of the Greek alphabet.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.