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

cold snap

a short period of cold weather

Word of the Day

Cleavage proves divisive in Cambridge’s words of 2014

by Alastair Horne,
December 19, 2014
​​​​ Other dictionaries may choose faddish novelties as their words of the year, but here at Cambridge, we like to do something different. We look for the words that have seen sudden surges in searches over the course of the year – words that have been baffling users of English and driven them

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