“Sigma upsilon” is normally read as the two Greek letter names, sigma and upsilon , not as “sy.”

When “sy” might happen

  • In English, people sometimes compress Greek-letter names when they’re using them as initials, abbreviations, or branding.
  • But that is a nickname-style reading, not the standard pronunciation of the letters themselves.
  • For actual Greek-letter reading, σ/ς = sigma and υ = upsilon.

Quick rule

  • If you’re reading the letters as Greek letters, say “sigma upsilon.”
  • If you’re looking at an abbreviation or group name that people have informally shortened, “sy” could be a local convention, but it is not the standard reading of the letters.

Example

  • ΣΥ would be read aloud as “sigma upsilon.”
  • Someone writing “SY” for short is usually just using initials, not the Greek pronunciation.

TL;DR

“Sigma upsilon” is usually read literally as sigma upsilon , and only sometimes shortened informally to something like “sy” depending on context.