Software
In 1970s less than 1 percent of the public could have intelligently explained what "computer software " means. Nowadays most professionals and various member of the public at large feel that they understand software. But do they really?
A textbook explanation of software might take the following form: Software is (1) instructions (computer programs) that when executed give desired function and performance (2) data structures that allow the programs to sufficiently manipulate information and (3) documents that explain the operation and application of the programs. There is no question that other more full definitions could be given. But we require more than a formal definition.