1. to breathe rapidly and deeply, often involuntarily, usually as a result of anxiety, panic, or physical exertion
Usage: transitive or intransitive
2. to become extremely excited, anxious, or agitated
Usage: informal; figurative

Examples

• She began to hyperventilate when she heard the news about the accident.
• The athlete hyperventilated before the big race, trying to calm his nerves.
• During the panic attack, he couldn't stop hyperventilating despite his efforts to breathe slowly.
• Don't hyperventilate about the test—you've studied hard and you'll do fine.
• The crowd started to hyperventilate with excitement as the band took the stage.
• When anxious, some people hyperventilate without even realizing it.
• She hyperventilated so much that she felt dizzy and lightheaded.