• heart-burn

From Middle English hertbryne, herte-bren (“lust", also "heartburn”, literally “heart burn”), equivalent to heart +‎ burn. Compare also Middle English herte-brennyng (“anger, bitterness, heartburn”, literally “burning of/in the heart, heart-burning”). Compare also Ancient Greek καρδιαλγία (kardialgía), from καρδία (kardía, “heart”) + ἄλγος (álgos, “pain”). From being a burning sensation near the location of the heart in the chest.

heartburn (countable and uncountable, plural heartburns)

1. (pathology) A burning pain in the chest that is caused by stomach acid entering the gullet.

   Synonyms: acid reflux, gastric reflux, gastroesophageal reflux, pyrosis, water brash, (archaic) cardialgia, cardialgy

   Hypernym: indigestion

   Coordinate term: cardiodynia

2. (Can we verify⁽⁺⁾ this sense?) (figuratively) Synonym of annoyance (“state of being annoyed”)
   • 2001, J. Michael Willard, The Accidental Headline, →ISBN, page 80:

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

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

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

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

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

   • 2013, Kenneth Conboy, The Cambodian Wars, →ISBN, page 268:

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

• heartburn on Wikipedia.Wikipedia