Why was spy plane called U2?

The U-2 spy plane was not named due to its purpose, but rather due to its design and intended flight characteristics. The "U" in U-2 stands for "utility," as the aircraft was originally intended to be a high-altitude, long-range reconnaissance aircraft capable of performing various tasks. The "2" in U-2 was simply the next number in sequence after the previous Lockheed-designed aircraft, the U-1.