upsilon

American  

[yoop-suh-lon, -luhn, uhp-, yoop-sahy-luhn] / ˈyup səˌlɒn, -lən, ˈʌp-, yupˈsaɪ lən /

noun

1. the 20th letter of the Greek alphabet (Υ, υ).

2. the vowel sound represented by this letter.

3. 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. Υ, υ

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upsilon British  

/ ˈʌpsɪˌlɒn, juːpˈsaɪlən /

noun

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

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Etymology

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 )

Example Sentences

They named the signal upsilon, after the shape of the decay-particle trajectories, which resembled the Greek letter.

From Nature

We have described under iota the custom of placing dots, &c. over upsilon.

From Project Gutenberg

Instead, the limited evidence now available suggests that T. tau and T. upsilon are names based on a highly variable character of color pattern of the head, and that only one species is involved.

From Project Gutenberg

Changed what appeared to be upsilon with inverted breve to upsilon with perispomeni in the Greek on page 2.

From Project Gutenberg

A bone of the tongue resembling the Greek letter upsilon in shape.

From Project Gutenberg