| Definition -
A grammatical structure in which a statement is turned into a question by adding an
interrogative fragment (i.e. the tag), such as isn't it or aren't they.
1. American grammarians call them tag questions, whereas British grammarians prefer the term question tag.
2. Some linguists believe that this structure is actually an assertion, not a question.
Example - She isn't leaving, is she?
Oxford English Dictionary - The term's first citation is from 1933:
"Note especially *tag-questions … like: He was angry, wasn't he?"
(O. Jespersen Essentials Eng. Gram. xxviii. 304)