Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “SI”

See all translations

SI

noun [U] uk   /esˈaɪ/ specialized us  
abbreviation for Système International: the international system of units used for scientific measurements, with standard base units such as the metre and the kilogram: The SI unit of electric current is the ampere.
(Definition of SI from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of SI?
Add Cambridge dictionaries to your browser to your website

More meanings of “SI”

Definitions of “SI” in other dictionaries

Word of the Day

glacial

made or left by a glacier

Word of the Day

Let’s celebrate! (words and phrases for parties)

by Kate Woodford,
December 17, 2014
​​​ With Christmas and New Year almost upon us, we thought it a good time to look at the language of parties and celebrations. First, let’s start with the word ‘party’ itself. To have or throw a party or, less commonly, to give a party is to arrange a party: We’re having a

Read More 

cinderella surgery noun

December 15, 2014
cosmetic surgery to the feet We have all heard of people having nose jobs, boob jobs and liposuction – but now a new trend growing in popularity in America: Cinderella surgery.

Read More