sly

adjective

ˈslī 

slyer also slier ˈslī(-ə)r  ; slyest also sliest ˈslī-əst 

1

chiefly dialectal

a

: wise in practical affairs

b

: displaying cleverness : ingenious

2

a

: clever in concealing one's aims or ends : furtive

b

: lacking in straightforwardness and candor : dissembling

3

: lightly mischievous : roguish

a sly jest

slyly adverb

or less commonly slily

She slyly evaded the question.

slyness noun

Phrases

on the sly

: in a manner intended to avoid notice

Synonyms

• artful
• beguiling
• cagey
• cagy
• crafty
• cunning
• cute
• designing
• devious
• dodgy [chiefly British]
• foxy
• guileful
• scheming
• shrewd
• slick
• subtle
• tricky
• wily

Choose the Right Synonym for sly

sly, cunning, crafty, wily, tricky, foxy, artful, slick mean attaining or seeking to attain one's ends by guileful or devious means.

sly implies furtiveness, lack of candor, and skill in concealing one's aims and methods.

a sly corporate raider

cunning suggests the inventive use of sometimes limited intelligence in overreaching or circumventing.

the cunning fox avoided the trap

crafty implies cleverness and subtlety of method.

a crafty lefthander

wily implies skill and deception in maneuvering.

the wily fugitive escaped the posse

tricky is more likely to suggest shiftiness and unreliability than skill in deception and maneuvering.

a tricky political operative

foxy implies a shrewd and wary craftiness usually involving devious dealing.

a foxy publicity man planting stories

artful implies indirectness in dealing and often connotes sophistication or cleverness.

elicited the information by artful questioning

slick emphasizes smoothness and guile.

slick operators selling time-sharing

Examples of sly in a Sentence

the movie pairs a sly, dissembling ex-con with an upstanding, straight-arrow cop

why, you sly fellow! I had no idea you were planning my birthday party

Recent Examples on the Web

Here are six real books coming out this week, with dust jackets that reflect their real contents: mysteries and mishaps, often told with a sly smirk. —Colin Dwyer, NPR, 1 Apr. 2025

In a perfectly coifed wig, with a sly smile and endless witticisms, Snook takes on 26 different roles across the show's nearly two hour runtime. —Shania Russell, EW.com, 28 Mar. 2025

These are the intriguing ideas at work in Secret Mall Apartment, but the film works as a movie thanks to the sly way it’s been put together. —Bilge Ebiri, Vulture, 21 Mar. 2025

Saxon looks stunned, but his younger bro wears a sly smile. —Amanda Whiting, Vulture, 16 Mar. 2025

Word History

Etymology

Middle English sleighe, sli, from Old Norse slœgr; akin to Old English slēan to strike — more at slay

First Known Use

13th century, in the meaning defined at sense 1a

Rhymes for sly

• ai
• aye
• bae
• bi
• buy
• by
• bye
• chai
• chi
• cry
• die
• dry

Kids Definition

sly

adjective

ˈslī 

slier or slyer ˈslī(-ə)r  ; sliest or slyest ˈslī-əst 

1

a

: clever at hiding one's goals or purpose

b

: tending to secrecy or concealment

2

: lightly mischievous

a sly smile

slyly adverb

slyness noun