sly

1 of 2

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

see also:

on the sly

slyly

2 of 2

adverb

sly·​ly

variants or less commonly slily

: in a sly manner: such as

a

: shrewdly

pointed his remarks by slyly wagging his forefinger

—G. B. Shaw

b

: with covert cunning : subtly

offered her slyly insolent condolences on being married to a barbarian

—Charles Kingsley

c

: in a surreptitious way : furtively

glanced slyly

slyly in love with their colleagues

—H. T. Moore

slyly injected commercials

—New Yorker

d

: artfully, roguishly

Synonyms of sly

Adjective

• cunning
• cute
• subtle
• slick

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

Adjective

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

Adjective

Yes, a few zingers hit their target, and some sly innuendoes tap into He-Man’s gay following. —Randy Myers, Mercury News, 3 June 2026

Leto, who has done more than a few of these kinds of villainous cartoon characters, brings some scene-stealing sly humor and sharp line readings to his despicable Skeletor with a voice that sounds like a cross between James Earl Jones and Sir Ian McKellen. —Pete Hammond, Deadline, 2 June 2026

Instead, Navarrette explained, the One Wish Willow company’s name — TABI Cat Curiosities — is a sly reference to the YouTube comedy series Curry Barker created with Cooper Tomlinson in 2020. —Tim Lammers, Forbes.com, 26 May 2026

Garcia sets this all up in a sly way, without overstating it. —Owen Gleiberman, Variety, 21 May 2026

Word History

Etymology

Adjective

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

Adverb

Middle English slily, from sli sly + -ly

First Known Use

Adjective

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

Phrases Containing sly

• on the sly

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