Definition of sly in English:

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Pronunciation: /slī/

adjective (slyer, slyest)

1Having or showing a cunning and deceitful nature: she had a sly personality
More example sentences
  • Those raised in urban Western understanding of the psychology of the animal kingdom tend to view the fox as a cunning, sly, deceitful animal.
  • She was a rather cunning and sly teenager by nature, accented by her narrow brown eyes and usual smirk.
  • When Chinese describe a person as ‘a monkey’, it means the person is extremely sly or cunning.
cunning, crafty, clever, wily, artful, guileful, tricky, scheming, devious, deceitful, duplicitous, dishonest, underhanded, sneaky
archaic subtle
1.1(Of a remark, glance, or facial expression) showing in an insinuating way that one has some secret knowledge that may be harmful or embarrassing: he gave a sly grin
More example sentences
  • He couldn't resist what appeared a sly dig at the directors of Dundee, suggesting that by refusing to accept his offer to invest, they were willing to risk their club's financial well-being.
  • He seems touched but then can't resist having a sly dig at himself by pointing out that the really tender thing to have done would have been not to include it on the album.
  • Stan nodded conspiratorially, a sly grin creeping over his face.
roguish, mischievous, impish, playful, wicked, arch, knowing
1.2(Of an action) surreptitious: a sly sip of water
More example sentences
  • Nelson took a sip of the wine and a sly smile appeared.
surreptitious, furtive, stealthy, covert


on the sly

In a secretive fashion: she was drinking on the sly
More example sentences
  • Unfortunately, the train to my conference left at 4 AM after a night spent trying to acquire a travel visa on the sly, which meant drinking a lot of vodka.
  • And there still is such a thing as scavenging on the sly - sneaking into dumpsters for the great find.
  • Younger and wirier than his charge, talking a mile a minute and singing during his chores, he nonetheless shows a careworn, weary face, and he drinks on the sly.
in secret, secretly, furtively, surreptitiously, covertly, clandestinely, on the quiet, behind someone's back
informal on the QT



Pronunciation: /ˈslīnəs/
Example sentences
  • He can pull a prank with craftiness and slyness, so cunningly that even the heroes of war would not be able to spot it.
  • He seems to know all the possible ways one might lie-with craftiness, slyness, deception.
  • ‘The slyness was a horrible moral and personal version of spots,’ he says, ‘and I think I just grew out of it in a strange way.’


Middle English (also in the sense 'dexterous'): from Old Norse slœgr 'cunning', originally 'able to strike', from the verb slá; compare with sleight.

  • Early use of sly, which comes from Old Norse slœgr ‘cunning’, included the sense ‘dexterous, skilful’. The phrase on the sly is recorded in use from the early 19th century. Sleight (Middle English) is from the same source, and passed from the sense ‘cunning’ to ‘sleight of hand’ in the late 16th century.

Words that rhyme with sly

ally, Altai, apply, assai, awry, ay, aye, Baha'i, belie, bi, Bligh, buy, by, bye, bye-bye, chi, Chiangmai, Ciskei, comply, cry, Cy, Dai, defy, deny, Di, die, do-or-die, dry, Dubai, dye, espy, eye, fie, fly, forbye, fry, Frye, goodbye (US goodby), guy, hereby, hi, hie, high, I, imply, I-spy, July, kai, lie, lye, Mackay, misapply, my, nearby, nigh, Nye, outfly, passer-by, phi, pi, pie, ply, pry, psi, Qinghai, rai, rely, rocaille, rye, scry, serai, shanghai, shy, sigh, sky, Skye, sky-high, spin-dry, spry, spy, sty, Sukhotai, supply, Tai, Thai, thereby, thigh, thy, tie, Transkei, try, tumble-dry, underlie, Versailles, Vi, vie, whereby, why, wry, Wye, xi, Xingtai, Yantai

For editors and proofreaders

Syllabification: sly

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