A sullen child. A sullen child. Sullen means being withdrawn and appearing sad. An example of sullen is a child who dropped an ice cream on the ground. The definition of sullen is something that appears dull or dark.An example of sullen is the black or dark clothing at a funeral. sullen child. A sullen child. Sullen means being withdrawn and appearing sad. An example of sullen is a child who dropped an ice cream on the ground. The definition of sullen is something that appears dull or dark. An example of sullen is the black or dark clothing at a funeral.