scan

Etymology

From late Middle English scanne (“to mark off verse to show metrical structure”), from earlier scanden, from Late Latin scandere (“to scan verse”), from Classical Latin scandō (“I climb, rise, mount”), from Proto-Indo-European *skend- (“to jump, dart, climb, scale, scan”).

verb

1. (transitive) To examine sequentially, carefully, or critically; to scrutinize; to behold closely.
   She scanned the passage carefully but could not find what she was looking for.
   Yet the incident did not in the least diminish my respect for my teacher. I was by nature blind to the faults of elders. Later I came to know of many other failings of this teacher, but my regard for him remained the same. For I had learnt to carry out the orders of elders, not to scan their actions. 1927-29, M.K. Gandhi, The Story of My Experiments with Truth, translated 1940 by Mahadev Desai, Part I, Chapter ii
   As the 1857 to Manchester Piccadilly rolls in, I scan the windows and realise there are plenty of spare seats, so I hop aboard. The train is a '221'+'220' combo to allow for social distancing - a luxury on an XC train as normally you're playing sardines, so I make the most of it. December 2 2020, Paul Bigland, “My weirdest and wackiest Rover yet”, in Rail, page 68
2. (transitive) To look about for; to look over quickly.
   1. (computing, transitive) To inspect, analyse or go over, often to find something.
      to scan the hard drive for errors
   2. (computing, transitive) To perform lexical analysis; to tokenize.
3. (computing, medicine, transitive) To create an image of something with the use of a scanner.
   to scan a photograph
   to scan internal organs by means of computed tomography
   Pencil drawings don't scan very well.
4. (computing, transitive) To read with an electronic device.
   to scan a barcode
   to scan a QR code
5. (obsolete, transitive, originally) To mount by steps; to go through with step by step.
6. (poetry, transitive) To read or mark so as to show a specific metre.
   to scan verse
   1. (intransitive) To conform to a metrical structure.
      You're right, sir, it doesn't scan very well in the English, but in the Gaelic it's sheer poetry. Have you the Gaelic? 1998, Milton Acorn, Cedric Smith, edited by James Deahl, The Road to Charlottetown: A Play, UnMon Northland

noun

1. Close investigation.
2. (computing) An instance of scanning.
   The operators vacated the room during the scan.
3. (computing) The result or output of a scanning process.
   The doctors looked at the scans and made a diagnosis.