heartburn UK /ˈhɑːtˌbɜːn/US /ˈhɑɹtˌbɝn/ noun2 •A burning pain in the chest that is caused by stomach acid entering the gullet. •(figurative) annoyance, heartache, or similar feelings.”There’s some heartburn about the fact the message is getting stepped on,” said Mark McKinnon, Bush’s campaign media strategist. — 2001 formsheartburns