has become embroiled in a row with West Country bakers after telling American tourists that a British "pastie" is a "meat pie".
The fast-food giant uses the description in a visitor guide to useful English words.
Pasty makers in Devon and Cornwall described the comparison as "incredible".
Phil Abbott, director of Plymouth-based Ivor Dewdney Pasties, said: "I'm sure people will find it very funny to hear a pasty described as a 'meat pie' … A pasty isn't a meat pie. A meat pie is a meat pie.
A pasty is wrapped in pastry. A pie has crust. And a pasty contains a lot more than meat."
He added: "McDonald's should know better – and they should know how to spell pasty. It's like calling a Big Mac a beef sandwich.
"If American tourists want a meat pie when they're in England, they should simply ask for a meat pie."
Mark Muncey, chairman of the Cornish Pasty Association, said the two were different, adding: "We are confident that many visitors to the Olympics will have enjoyed a real pasty during their visit and been able to make the distinction for themselves."
McDonald's, a sponsor of the Olympics, defines "pastie" in a list of Useful Words for Visiting London, found on the cover of its commemorative London 2012 reporter's notebook.
The list also includes: "gobsmacked" – which means "amazed"; "bobby" – which means "policeman"; "cheerio" ("goodbye"); "grub" ("food"); "biscuit" ("cookie"); "sarnie" ("sandwich"); and "fancy a Big Mac?" – which means "would you like a Big Mac?"
A McDonald's spokeswoman did not respond to a request for comment.