Dictionary.com

upsilon

[ yoop-suh-lon, -luhn, uhp-; especially British yoop-sahy-luhn ]
/ 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

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Origin of upsilon

First recorded in 1615–25; from Late Greek ŷ psīlón, literally, “simple u” (to distinguish it from the digraph oi, pronounced the same in Late Greek )

Words nearby upsilon

upside, upside down, upside-down cake, upsides, upside the head, upsilon, upsilon particle, upsize, upskill, upspin, upspring
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for upsilon

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

Medical definitions for upsilon (1 of 2)

upsilon

n.

The 20th letter of the Greek alphabet.

Medical definitions for upsilon (2 of 2)

υ

The Greek letter upsilon. Entries beginning with this character are alphabetized under upsilon.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.