Fulgid means shining brightly or radiantly. The antonym for this word is dull or murky. While fulgid is associated with brilliance and glowing, in contrast, dull denotes a lack of brightness or shine. Other antonyms for fulgid could be gloomy, dingy, or murky, which all signify a lack of brightness or light. Conversely, sparkling and glittering could be considered synonyms of the word fulgid, as they also refer to bright or shining things. In general, the antonyms for fulgid pertain to darkness or a lack of brightness, while its synonyms are more about brightness and shine.