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

• cunning
• cute
• subtle

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

When Kelce started dating pop star and his now-fiancée, Taylor Swift, in 2023, Nicole notably came under scrutiny for seemingly unfollowing one of Kelce’s teammates on Instagram and recently for making a sly response to a new Swift track that appears to reference her previous romance with Kelce. —Luke Chinman, PEOPLE, 14 Oct. 2025

Gigi Zumbado is a sly scene-stealer as Ceci, the department’s relatively cool and confident and young photographer, but hasn’t been given much to do besides snark from the sidelines. —Angie Han, HollywoodReporter, 13 Oct. 2025

At school, teachers hid their identities and students made sly side comments. —Greta Cross, USA Today, 11 Oct. 2025

Presenting Linda with two open wounds—one in the ceiling, and one in her child’s flesh—the film suggests, with sly wit and bristling optimism, that the solutions to both problems might be one and the same. —Justin Chang, New Yorker, 9 Oct. 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