si
noun
the syllable used for the seventh tone of a scale and sometimes for the tone B.
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si
1 American
[see]
/ si /
noun
Music.
Si
2
American
Symbol, Chemistry.
SI
3
American
abbreviation
S.I.
4
American
abbreviation
-
Sandwich Islands.
-
Staten Island.
SI
1
British
symbol
abbreviation
Si
2
British
/ ʃiː /
noun
Si
3
British
symbol
si
4
British
/ siː /
noun
si
5
British
abbreviation
Etymology
Origin of si
First recorded in 1720–30; see origin at gamut
Vocabulary lists containing si
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Both had the same question embroidered on them: “¿Y si sí?”
From Los Angeles Times ● Jul. 5, 2026
It opens with a big-band cover of the 1920 standard “Whispering,” leading into the track, and closes with a reference to the 1947 French cabaret song “C’est si Bon.”
From The Wall Street Journal ● Jun. 15, 2026
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
So the crowd-pleasing sound world of Liszt returned one last time with “Enfant, si j’étais roi.”
From New York Times ● Sep. 8, 2022
When I was little and I got the slightest injury, Mami, Papi, Abue, Toño—whoever was closest—patted my hurt and said to me this: Sana, sana, colita de rana, si no sanas hoy, sanarás mañana.
From "Beast Rider" by Tony Johnston & María Elena Fontanot de Rhoads
I saved up and bought a red 1989 Honda CRX Si.
From Los Angeles Times ● Jun. 22, 2026
To test the theory, Fang and Si conducted laboratory experiments using a thin layer of water driven by electromagnetic forces.
From Science Daily ● Jun. 3, 2026
He and his brother Si were close—but also very different, according to “Citizen Newhouse,” a book about the family by Carol Felsenthal.
From The Wall Street Journal ● May 27, 2026
Experts say "Magnifica Humanitas" could prove as influential as Pope Francis's "Laudato Si", a 2015 climate manifesto that triggered political and civic reactions worldwide.
From Barron's ● May 25, 2026
Purple Latin words stretched in a long ribbon beneath the seal: Si Quaeris Peninsulam Amoentrm Cir- cumspice.
From "Song of Solomon" by Toni Morrison
The painting, which came from the private collection of media magnate SI Newhouse, is also now the fourth most expensive artwork ever sold at auction, according to ARTnews.
From BBC ● May 19, 2026
The memorial itself holds a "tiered system of commemoration", says Korean research company SI Analytics.
From BBC ● May 7, 2026
About 140 graves sit on the west side of the graveyard and 138 that sit on the opposite site, according to a satellite image taken in early April provided by SI Analytics.
From BBC ● May 7, 2026
In March 2024, Arena announced it was shutting down the print edition of SI.
From Los Angeles Times ● Apr. 5, 2026
Oct-ober SI “Did you give Tony my thank-you note?”
From "The Dead and the Gone" by Susan Beth Pfeffer
Both the Pollock and the Brancusi came from the estate of Condé Nast publisher S.I.
From The Wall Street Journal ● May 19, 2026
According to a new survey titled “The American Journalist Under Attack,” released by Syracuse University’s S.I.
From Washington Times ● Dec. 30, 2023
But he also edited The New Yorker for five years before departing over “conceptual differences” with publisher S.I.
From Seattle Times ● Jun. 14, 2023
According to a survey of TV news directors by Bob Papper, an adjunct professor at the S.I.
From New York Times ● Apr. 3, 2023
A wonderful incident is told by Dr. S.I.
From The Wonders of Prayer A Record of Well Authenticated and Wonderful Answers to Prayer by D. W. (Daniel Webster) Whittle
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
