Definition of "heartburn"

”There’s some heartburn about the fact the message is getting stepped on,” said Mark McKinnon, Bush’s campaign media strategist.

2001, J. Michael Willard, The Accidental Headline, page 80

America’s policy of containing both the Soviet Union and its Chinese ally did cause some heartburn in Tokyo.

2003, Robyn Lim, The Geopolitics of East Asia: The Search for Equilibrium, page 92

"It boils down to promises made, promises kept," said Mr. White, 53. "And that's really what I have heartburn about."

2005 December 14, Micheline Maynard, Jeremy W. Peters, “Protests Well Up as Delphi Workers Ponder Cuts”, in The New York Times

Back in Thailand, meantime, the CIA felt relatively little heartburn over the congressional rebuff.

2013, Kenneth Conboy, The Cambodian Wars, page 268