(countable & uncountable) Hyperbole is exaggeration. It is a type of figurative language commonly used in everyday speech, poetry, and literature. It makes something sound much better or much worse than it really is.
She told Leo her father had cooked enough food to feed an army. Leo thought that was just hyperbole until HE saw the food.
Marissa is the queen of hyperbole. Today she told me, "If I don't get those new shoes I'll just die. And I'm so hungry I could eat a horse."