Photography. any device for exposing an image on film, a sensitized plate, etc., by tracing light along a series of many closely spaced parallel lines.
4.
(in aerial photography) a device for estimating the ratio of aircraft speed to aircraft altitude.
5.
a photoelectric device for scanning a picture to determine automatically the density of the hue or value in each area for transmission by wire or radio or for preparation of color process printing plates.
6.
a computer-aided electronic system using photoelectric cells to separate copy, as color illustrations, into its primary colors, correct color copy, and produce a set of color separations ready for proofing or printing.
7.
Radio. a radio receiver, used especially by police, firefighters, and the press, that continuously tunes to preselected frequencies, broadcasting any signal that it detects.
8.
Medicine/Medical, Biology. a device for examining a body, organ, tissue, or other biologically active material.
For example, there are concerns that retina scanners might not always be clean.
British Dictionary definitions for scanners
scanner
/ˈskænə/
noun
1.
a person or thing that scans
2.
a device, usually electronic, used to measure or sample the distribution of some quantity or condition in a particular system, region, or area
3.
an aerial or similar device designed to transmit or receive signals, esp radar signals, inside a given solid angle of space, thus allowing a particular region to be scanned
(printing) an electronic device which scans printed material and converts it to digital form
Word Origin and History for scanners
scanner
n.
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.