Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “sly”

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.Secrecy and privacy [before noun] seeming to know secrets: "You'll find out eventually," said Mary with a sly smile.Secrecy and privacy
slyly
adverb uk   /ˈslaɪ.li/ us  
She grinned slyly and refused to tell me where the money came from.Secrecy and privacy
slyness
noun [U] uk   /ˈslaɪ.nəs/ us  
Secrecy and privacy

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.Secrecy and privacy
(Definition of sly from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of sly?
Browse related topics

You are looking at an entry to do with Secrecy and privacy, but you might be interested in these topics from the Showing and hiding topic area:

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

nip

to press something quickly and quite hard between two objects, especially sharp objects such as teeth or nails

Word of the Day

Blog

Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More