(slier or slyer; sliest or slyest)
Etymology: Middle English sleighe, sli, from Old Norse slœgr; akin to Old English slēan to strike — more at slay
Date: 13th century
1. chiefly dialect
a. wise in practical affairs
b. displaying cleverness ; ingenious
a. clever in concealing one's aims or ends ; furtive <the sly fox> b. lacking in straightforwardness and candor ; dissembling <a sly scheme> 3. lightly mischievous ; roguish <a sly jest> <a sly smile> • slyly also slily adverb • slyness noun Synonyms: 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>.
New Collegiate Dictionary. 2001.