I ate too much spicy food yesterday and had terrible heartburn at night.

heartburn 是由 heart（心脏）和 burn（燃烧）组成的复合词，字面意思是"心脏燃烧"。实际上指胃酸反流引起的胸部灼热感，医学上称为"胃灼热"或"烧心"。