Dictionary.com
definitions
  • synonyms

sly

[slahy]
See more synonyms for sly on Thesaurus.com
adjective, sly·er, sly·est.
  1. cunning or wily: sly as a fox.
  2. stealthy, insidious, or secret.
  3. playfully artful, mischievous, or roguish: sly humor.
Show More
Idioms
  1. on the sly, secretly; furtively: a tryst on the sly.
Show More

Origin of sly

1150–1200; Middle English sly, sley, from Old Norse slœgr “sly, cunning” (originally “able to strike, able to slay”); see slay
Related formssly·ly, adverbsly·ness, nounun·sly, adjective, un·sly·er, un·sly·est.un·sly·ly, adverbun·sly·ness, noun

Synonyms

See more synonyms for on Thesaurus.com
1. artful, subtle, foxy, crafty, shrewd, astute. 2. surreptitious, furtive, underhand, clandestine.

Antonyms

1. direct, obvious.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words

ingeniousintriguingimpishshrewdroguishmischievouscannysubtlesmartarchartfulastutecageycalculatingcaptiouscovertcraftycrookedcunningdeceitful

Examples from the Web for sly

Contemporary Examples

Historical Examples

  • "Let them sleep in the bed of honor," said the Princess Medea, with a sly smile at Jason.

    Tanglewood Tales

    Nathaniel Hawthorne

  • The sly, wicked Mimi came slinking to the place where the dragon lay.

  • I know her sly manner of feeling her way with those gloves of hers.

    Little Dorrit

    Charles Dickens

  • The faces seemed to have but one smile, conscious, sly, a little alarmed.

    The Coryston Family

    Mrs. Humphry Ward

  • But I had only to open my lips to speak, and away she would run, with a sly smile.

    A Hero of Our Time

    M. Y. Lermontov

British Dictionary definitions for sly

sly

adjective slyer, slyest, slier or sliest
  1. crafty; artfula sly dodge
  2. insidious; furtivea sly manner
  3. playfully mischievous; roguishsly humour
Show More
noun
  1. on the sly in a secretive manner
Show More
Derived Formsslyly or slily, adverbslyness, noun

Word Origin

C12: from Old Norse slǣgr clever, literally: able to strike, from slā to slay
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for sly

adj.

c.1200, "skillful, clever, dexterous," from Old Norse sloegr "cunning, crafty, sly," from Proto-Germanic *slogis (cf. Low German slu "cunning, sly," German schlau), probably from base *slak- "to strike, hit" (see slay (v.)), with an original notion of "able to hit." Cf. German verschlagen "cunning, crafty, sly," schlagfertig "quick-witted," literally "strike-ready," from schlagen "to strike." A non-pejorative use of the word lingered in northern English dialect until 20c. On the sly "in secret" is recorded from 1812. Sly-boots "a seeming Silly, but subtil Fellow" is in the 1700 "Dictionary of the Canting Crew."

Show More
Online Etymology Dictionary, © 2010 Douglas Harper

Idioms and Phrases with sly

sly

see on the sly.

Show More
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.