Scanner (band) definition

(1) A radio receiver that moves automatically across some selected range of frequencies looking for some signal or condition

"They used scanners to monitor police radio channels"

(2) A radar dish that rotates or oscillates in order to scan a broad area

(3) An electronic device that generates a digital representation of an image for data input to a computer

(4) Someone who scans verse to determine the number and prosodic value of the syllables