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• si
  si

  noun

  the syllable used for the seventh tone of a scale and sometimes for the tone B.
• Si
  Si

  silicon.
• SI
  SI

  abbreviation

  International System of Units.
• S.I.
  S.I.

  abbreviation

  Sandwich Islands.

si

¹ American  

[see] / si /

noun

Music.

1. the syllable used for the seventh tone of a scale and sometimes for the tone B.

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Si ² American  

Symbol, Chemistry.

1. silicon.

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SI ³ American  

abbreviation

1. International System of Units.

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S.I. ⁴ American  

abbreviation

1. Sandwich Islands.

2. Staten Island.

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SI ¹ British  

symbol

1. Système International (d'Unités) See SI unit

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abbreviation

1. South Island

Si ² British  

/ ʃiː /

noun

1. a variant transliteration of the Chinese name for the Xi

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Si ³ British  

symbol

1. silicon

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si ⁴ British  

/ siː /

noun

1. music a variant of te

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si ⁵ British  

abbreviation

1. Slovenia

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Etymology

Origin of si

First recorded in 1720–30; see origin at gamut

Example Sentences

Cuando le preguntaron si los aficionados del Citizens Bank Park se burlaban de él, respondió que no entendía lo que decían.

From Los Angeles Times • Oct. 10, 2025

“No sé si es más fácil o más difícil que ganáramos el año pasado”, dijo Roberts.

From Los Angeles Times • Sep. 30, 2025

She claims she even uses words and mannerisms such as "mamma mia", "bambino" and "si" in conversation without realising it.

From BBC • Dec. 22, 2024

Para muchos investigadores, la gran pregunta es si, de ser electa, Sheinbaum Pardo continuará, revisará, o incluso revertirá las impopulares políticas relacionadas con la ciencia de su mentor.

From Science Magazine • May 8, 2024

Then he adds a final note: “Perché la minesstra si fredda.”

From "The Mona Lisa Vanishes" by Nicholas Day