Airmail is mail transported by airplane rather than by truck, train, or ship. Before airmail became common in the 1920s, a letter from New York to California might take a week or more by train. The same letter sent by airmail could arrive in just a day or two.

Airmail revolutionized communication. Suddenly, businesses could coordinate across continents, families separated by oceans could exchange news while it was still fresh, and urgent documents could reach their destinations quickly. During World War II, soldiers overseas relied on airmail to stay connected with loved ones back home.

Today, nearly all long-distance mail travels by air, so we don't usually distinguish it with a special term anymore. But you'll still see airmail on international letters, sometimes with distinctive red and blue striped borders on the envelope. When someone says they'll send something by airmail, they're promising speed: your letter will fly rather than crawl across the distance.

The word can also be used as a verb. A business might airmail an urgent contract to a client overseas, or you might airmail a birthday card to your cousin in another country so it arrives on time.