An iDevice generally refers to any Apple mobile device that runs Apple's iOS operating system, which includes the iPhone, iPad and iPod. Depending on context, the term could include Apple's TV set-top box, which also uses iOS. See iPhone
, iPod touch
, Apple TV
Lower case "i" Is a Popular Prefix
For Apple devices and even retail stores that cater to today's digital lifestyle, the "i" is a popular designation. Canadian-based iStore has retail outlets in more than a dozen airports in Canada and the U.S. This one is in the Phoenix, Arizona airport.