IPA: /ˈslaɪnəs/
KK: /slaɪnəs/
The quality or state of being clever in a deceitful way, often to achieve one's goals.
His slyness allowed him to outsmart his competitors.
Slyness → It is formed from "sly" (from Old Norse *slyðr*, meaning cunning or crafty) and "-ness" (meaning the state or quality of). The word "slyness" refers to the quality of being cunning or deceitful.
Think of the word 'sly' which means cunning or crafty, and remember that 'slyness' describes the state of being sly.