Is curly an adverb or adjective?

"Curly" is typically an adjective. It describes a noun, like "curly hair" or "a curly mustache."

While it's possible to use "curly" in an adverbial sense, it's not common. For example, you might say, "The dog's tail wagged curly," meaning it wagged in a curled or curled-up way. However, this usage is more unusual and often seen as a poetic or figurative expression.