Providing shade or shelter from sunlight; also informally meaning suspicious, dishonest, or of questionable character. Having areas of shadow or darkness.
From Old English 'sceadig', from 'sceadu' (shadow, shade). The slang meaning of 'dishonest' emerged in the 20th century, metaphorically connecting physical darkness with moral darkness or hidden activities.
The evolution of 'shady' from 'pleasantly cool' to 'morally suspect' reflects the universal human association of darkness with hidden danger or deception. A shady spot under a tree offers relief, while a shady character offers trouble - same word, opposite desirability.
Complete word intelligence in one call. Free tier — 50 lookups/day.