1. To examine closely.
2. To look over quickly and systematically: scanning the horizon for signs of land.
3. To look over or leaf through hastily: scanned the newspaper while eating breakfast.
4. To analyze (verse) into metrical patterns.
5. Electronics
   1. To move a finely focused beam of light or electrons in a systematic pattern over (a surface) in order to reproduce or sense and subsequently transmit an image.
   2. To move a radar beam in a systematic pattern over (a sector of sky) in search of a target.
6. Computer Science To search (stored data) automatically for specific data.
7. Medicine To examine (a body or body part) with a CAT scanner or similar scanning apparatus.
8. To digitally encode (text, for example) with an optical scanner.

1. To analyze verse into metrical patterns.
2. To conform to a metrical pattern.
3. Electronics To undergo electronic scanning.

1. The act or an instance of scanning.
2. Scope or field of vision.
3. 1. Examination of a body or body part by a CAT scanner or similar scanning apparatus.
   2. A picture or image produced by this means.
4. A single sweep of the beam of electrons across a television screen.

Word History: In the 1969 edition of The American Heritage Dictionary a dead issue was buried by our Usage Panel, 85 percent of whom thought it was acceptable to use scan in the sense "to look over quickly," though the note stated that this was less formal usage. The usage issue was raised because scan in an earlier sense meant "to examine closely." From a historical perspective it is easy to see how these two opposite senses of scan developed. The source of our word, Latin scandere, which meant "to climb," came to mean "to scan a verse of poetry," because one could beat the rhythm by lifting and putting down one's foot. The Middle English verb scannen, derived from scandere, came into Middle English in this sense (first recorded in a text composed before 1398). In the 16th century this highly specialized sense having to do with the close analysis of verse developed other senses, such as "to criticize, examine minutely, interpret, perceive." From these senses having to do with examination and perception, it was an easy step to the sense "to look at searchingly" (first recorded in 1798), perhaps harking back still to the careful detailed work involved in analyzing prosody. The sense of looking something over to find a specific set of things was eventually broadened to include looking over the surface of something, with or without close scrutiny of the details. From this was born the modern usage of scan as a verb meaning "look over quickly."