Know how to use "fewer" and "less"? Find out.
1550s, "person who examines critically," agent noun from scan (v.). From 1927 as a type of mechanical device, in mid-20c. use especially of radar and medical devices; later of computer accessories.
1. An input device that takes in an optical image and digitises it into an electronic image represented as binary data. This can be used to create a computerised version of a photo or illustration.
A scanner may be linked to optical character recognition software allowing printed documents to be converted to electronic text without having to type them in at a keyboard.
2. lexical analyser.