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

piglet

a baby pig

Word of the Day

I won’t tolerate it! Replacing formal words with phrasal verbs.

by Liz Walter,
April 01, 2015
When you are using a language, it is important to understand if a word is formal or informal, so that you can use it in an appropriate way. You might hear people saying dosh for money, or spud for potato, but they wouldn’t write those words in a formal essay. Similarly, a

Read More 

stackin’ p

March 30, 2015
idiom slang earning a lot of money ‘That’s a very generous present.”Yeah, well, she’s stackin’ p, innit?’

Read More