sulk·y / ˈsəlkē/ • adj. (sulk·i·er, sulk·i·est) morose, bad-tempered, and resentful; refusing to be cooperative or cheerful: disappointment was making her sulky. ∎ expressing or suggesting gloom and bad temper: she had a sultry, sulky mouth. ∎ fig. not quick to work or respond: a sulky fire.• n. (pl. sulk·ies) a light two-wheeled horse-drawn vehicle for one person, used chiefly in harness racing.DERIVATIVES: sulk·i·ly / -kəlē/ adv.sulk·i·ness n.