shirttail Syllabification: (shirt·tail)Pronunciation: /ˈSHərˌtāl/Definition of shirttail noun (also shirttails) the lower, typically curved, part of a shirt that comes below the waist. adjective (of relatives) distantly related:if you checked back far enough, they were shirttail cousins of Curly’s parentsshirttail in other Oxford dictionaries Definition of shirttail in the British & World English dictionary