n. People who are skilled at using their thumbs to manipulate objects such as cell phone keys, small joysticks, and notebook computer pointers.
2002
Indeed, Japan is the model for a wireless-entertainment culture. NTT DoCoMo, that country's largest wireless company, has surprised and transformed the nation with a service called "I-mode," which allows subscribers to access games and other online entertainment wirelessly. The i-mode service requires a special cell phone with a slightly larger than ordinary screen (typically three by four centimeters). . . . I-mode is phenomenally popular, engendering a "thumb culture" of 30 million subscribers—an estimated 80 percent of people worldwide who currently use wireless devices to connect to the Net.
2000 (earliest)
Young Japanese have become so adept at their phones — manipulating a set of cursor keys or a button-sized joystick by thumb — that some people refer to a new 'thumb culture'.
Another name for the thumb-proficient is the thumb generation. In Japan, they're called oyayubizoku, which means "clan of the thumbs" or "thumb tribe."