What adjective describes a person who is sad or sulky?

The adjective that describes a person who is sad or sulky is "sullen." This word conveys a sense of gloominess or a disposition that is marked by a brooding or morose demeanor. A sullen individual typically shows little interest in participating in social interactions and may appear withdrawn or resentful. This term effectively captures the emotional state of someone who is not just sad, but whose sadness manifests in a silent, perhaps even stubborn, refusal to engage with others or to shake off their downcast mood.

In contrast, the terms "urbane," "witty," and "vivid" describe characteristics that do not align with a sulky disposition. "Urbane" refers to someone who is sophisticated and polished in manners or style—attributes far removed from sulkiness. "Witty" denotes a quick and inventive humor, which indicates a cheerful and engaging personality, not one that is sad. "Vivid" relates to the brightness or intensity of colors, imagery, or ideas, further illustrating a concept that is lively and dynamic, opposite of the somberness implied by "sullen."