upsilon

noun

up·​si·​lon ˈüp-sə-ˌlän  ˈyüp- 

ˈəp-,

-lən,

 British usually  yüp-ˈsī-lən

1

: the 20th letter of the Greek alphabet see Alphabet Table

2

: any of a group of unstable electrically neutral elementary particles of the meson family that have a mass about 10 times that of a proton

Examples of upsilon in a Sentence

Recent Examples on the Web

The team is hoping to spot composite particles called upsilons, for example. —Clara Moskowitz, Scientific American, 14 Feb. 2023

Word History

Etymology

Middle Greek y psilon, literally, simple y; from the desire to distinguish it from oi, which was pronounced the same in later Greek

First Known Use

1621, in the meaning defined at sense 1

Kids Definition

upsilon

noun

up·​si·​lon ˈyüp-sə-ˌlän  ˈəp- 

-lən

: the 20th letter of the Greek alphabet

—Υ or υ