A language expert from Japan has made a special mission back to England to find out more about two words he remembers from childhood for a new book.
Stephen Howe, an associate professor in English at Fukuoka University, has launched a study on the East Anglian dialect words "jearse" and "dow".
They mean an absolute yes or no and he has urged people to fill in a survey.
"They have not been published in the Oxford English Dictionary... so no-one knew about them," said Mr Howe.
Jearse and dow have been spoken across the east of England, including around Ely, Cambridgeshire, where Mr Howe grew up.
The historical linguist said his father still uses the words and remembers it was common for his grandparents to say them too.
"I think older people will remember them in Norwich and other parts of Norfolk, Suffolk, Cambridgeshire and Lincolnshire," said Mr Howe.
"We all know these words like 'aye' from the north of England and 'yay', 'nay', but in the east of England we have these special words 'jearse' and 'dow'.
"I, and the other local people here, always knew about them and I want to find out more."
Mr Howe has flown back from Japan, where he has lived for eight years, to research his chapter in a book on south of England dialects.
Earlier this year, he gave a talk at Cambridge University on the words and now wants to uncover how widely they are used.
He said he thought their origins are rooted in "dear yes" and "dear no", but hopes his project can find out for certain.