Word.ws English Dictionary

si

/siː/

si noun: a syllable used in solfège to represent the seventh note of a major scale.

Noun (1)

si (plural sis)

  1. A syllable used in solfège to represent the seventh note of a major scale.

Proper noun (1) capitalized: SI

SI

  1. International System of Units
    • The reason for the change to the International System of Measurement (SI) units was that over time the prototype lost atoms and therefore mass because it is “susceptible to damage and environmental factors,” according to the National Physical Laboratory (NPL), which houses Kilo 18, Britain’s copy...2018 November 13, Matthew Robinson and Lianne Kolirin, “The world has just redefined the kilogram”, in CNN

Proper noun (2) capitalized: SI

SI

  1. (abbreviation, initialism) Initialism of Smithsonian Institution.
  2. (abbreviation, initialism) Initialism of Sports Illustrated.
    • “We have said from the start that our top priorities are to keep Sports Illustrated alive, uphold the legacy of the institution and protect our union jobs. We look forward to discussing a future with Minute Media that does that,” Emma Baccellieri, staff writer for SI and vice chair for the SI...2024 March 18, Oliver Darcy and Liam Reilly, “Sports Illustrated to avert shutdown as it gets a fresh start under new publisher”, in CNN Business

Noun (2) capitalized: SI

SI (countable and uncountable, plural SIs)

  1. (abbreviation, initialism) Initialism of signal integrity.
  2. (abbreviation, initialism) Initialism of systems integration.
  3. (abbreviation, initialism) Initialism of self-injury.
  4. (abbreviation, initialism) Initialism of suicidal ideation.
  5. (abbreviation, initialism, slang) Initialism of self-insertion (of the author into fan fiction).
  6. (abbreviation, initialism) Initialism of spark ignition.
  7. (abbreviation, initialism) Initialism of supporting information.
  8. (abbreviation, initialism) Initialism of special intelligence.
  9. (abbreviation, initialism) Initialism of systematic internaliser.
  10. (abbreviation, initialism) Initialism of swarm intelligence.
  11. (abbreviation, initialism) Initialism of synthetic intelligence.
  12. (Philippines, abbreviation, initialism) Initialism of sales invoice.
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  1. (Australia, Canada, UK, abbreviation, initialism) Initialism of statutory instrument.
    • The scope of SIs varies greatly, from the technical (e.g. to set or vary the dates on which different provisions of an Act will come into force, to change the levels of fines or penalties for offences or to make consequential and transitional provisions) to the much wider-ranging, such as filling...2016 December 15, Richard Kelly, Statutory Instruments, House of Commons Library Briefing Paper 6509, archived from the original on 07 Jan 2022, page 1
  2. (abbreviation, initialism) Initialism of subinspector (of police, etc).
    • India's first transgender SI
  3. (abbreviation, initialism) Initialism of surface interval.

Adjective capitalized: SI

SI (not comparable)

  1. (abbreviation, initialism) Initialism of sacroiliac.
    • SI joint

Proper noun (3) capitalized: Si

IPA/saɪ/

Si

  1. A diminutive of the male given name Simon.
  2. A diminutive of the female given name Simone.
  3. A diminutive of the male given name Silas.

Proper noun (4) capitalized: Si

IPA/sɪ/

Si

  1. A river in Shandong, China.
  2. A county of Suzhou, Anhui, China.
    • Dong Xuefeng, head of the Huangwei Township Central School in Sixian County, Anhui province, told a school gathering on Monday that Christmas was a disgrace to the Chinese people because of past humiliations inflicted on the nation by mostly Christian invaders.[2018 December 26, Mandy Zuo, “Christmas linked to China’s past humiliation by foreign invaders in speech to primary schoolchildren”, in South China Morning Post, →ISSN, →OCLC, archived from the...
    • Si county in Anhui province locked down its 760,000 residents and suspended public traffic as it reported 288 cases on Saturday.2022 July 4, Sophie Yu, Stella Qiu, Ryan Woo, “Eastern China cities tighten COVID curbs as new clusters emerge”, in William Mallard, editor, Reuters, archived from the original on 05 Jul 2022...
    Synonyms:
    Sixian, Ssu-hsien
  3. (historical) Various prefectures of imperial China.
  4. (historical) A surname from Mandarin.

Proper noun (5) capitalized: Si

Si

  1. (alternative) Alternative form of Xi.

si meaning in Kannada, Punjabi, Gujarati and Arabic

si in Kannada

ಎಸ್. ಐ

si in Punjabi

ਐੱਸ. ਆਈ

si in Gujarati

એસ. આઈ

si in Arabic

seventh note of a major scale
سِي sī
More languagesFewer languages
si in Indonesian
si
si in Vietnamese
si

Examples of si in a sentence

  • I sat down in the armchair, and my sis sat down on the floor.
  • We're a place setting short, there'll be four of us - always supposing your sis really comes.
  • As your big sis, I worry about your life too.

All 31 example sentences with si

Synonyms of si

  • Sixian
  • Ssu-hsien
  • Sizhou
  • Ssu-chou

Forms of si

Noun
pluralsis
alternative formti
pluralSIs
alternative formS.I.
Proper noun
alternative formSy
alternative formSu
alternative formSsu
alternative formSzu

Plural of si: sis

Origin of si

From Middle English si (“seventh degree or note of Guido of Arezzo's hexachordal scales”), Italian si in the solmization of Guido of Arezzo, from the initials of Latin Sāncte Iohannēs (“Saint John (the Baptist)”) in the lyrics of the scale-ascending hymn Ut queant laxis by Paulus Deacon; thus, also an initialism of Sāncte Iohannēs.

Borrowed from French SI (“Système international d'unités”).

From clipping of various words beginning with the syllable /saɪ/.

Words formed from si

Phrases with si

Words that rhyme with si

48 more rhymesFewer rhymes

Questions about si

What does si mean?
Si means a syllable used in solfège to represent the seventh note of a major scale.
What is si in Kannada?
Si in Kannada is ಎಸ್. ಐ. See Si meaning in Kannada.
What part of speech is si?
Si can be a noun, a proper noun or an adjective.
How do you pronounce si?
Si is pronounced /siː/.
What is the plural of si?
The plural of si is sis.

Words near si in the dictionary

  1. shōnen-ai
  2. Shōwa
  3. shōyu
  4. shūmai
  5. Shūnan
  6. si
  7. SI joint
  8. SI joints
  9. si liao
  10. SI prefix
  11. SI prefixes

Source and license

Adapted from Wiktionary: si (page history and authors); SI (page history and authors); Si (page history and authors); si (Kannada, IndicTrans2 machine translation) (model and license); si (Punjabi, IndicTrans2 machine translation) (model and license); si (Gujarati, IndicTrans2 machine translation) (model and license). Text available under the Creative Commons Attribution-ShareAlike 4.0 license. Word.ws reformatted the entry and added links. Wiktionary data of 2026-09-02.

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Pronunciation audio from Wikimedia Commons, each file under its own free license: LL-Q1860 (eng)-Persent101-si.wav.

Cite this entry: “si.” Word.ws, https://word.ws/si. Based on Wiktionary, CC BY-SA 4.0.