Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “sly”

See all translations

sly

adjective uk   /slaɪ/ (slyer, slyest) us  
deceiving people in a clever way in order to get what you want: He's a sly old devil - I wouldn't trust him with my money. [before noun] seeming to know secrets: "You'll find out eventually," said Mary with a sly smile.
slyly
adverb uk   /ˈslaɪ.li/ us  
She grinned slyly and refused to tell me where the money came from.
slyness
noun [U] uk   /ˈslaɪ.nəs/ us  

sly

noun uk   /slaɪ/ us  
on the sly If you do something on the sly, you do it secretly because you should not be doing it: He drives his mother's car on the sly while she's at work.
(Definition of sly from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of sly?
Add Cambridge dictionaries to your browser to your website

“sly” in English

More meanings of “sly”

Definitions of “sly” in other dictionaries

Word of the Day

make believe

believing or imagining things that appear to be attractive or exciting, but are not real

Word of the Day

Lies, lies, lies!

by Kate Woodford,
February 25, 2015
​​​ According to sociologists (=people who study the relationships between people living in groups), we are good at lying. As a species, we have developed a remarkable ability to deceive each other (= persuade each other that something false is true). Being able to say things that are not true can help with

Read More 

showrooming noun

February 23, 2015
the activity of examining a product in a physical store and then making the purchase with an online retailer Amazon’s new smartphone is specifically designed to make showrooming fast and easy.

Read More