tap code
Wall-knock alphabet system
Tap code is a communication system using patterns of taps to represent letters, most associated with prisoners of war who used it to send messages through walls.
The alphabet is arranged in a grid, with each letter identified by two sets of taps—row then column: He tapped out a message to the cell next door.
The system allows covert communication when speech is impossible or forbidden.
- prisonerConfined criminal detainee
- knockStrike-produced sound
- wallVertical enclosing structure
- cipherHidden writing system
- signalMessage-conveying cue
POW · secret message · communication · finger · rhythm · secret · grid · cell · solitary confinement · message · pattern · dot · dash · alphabet · five by five · underground · resistance · interrogation
- codes and cipherscipher, decrypt, encrypt, ciphertext, plaintext
- secret codescipher, password, passphrase, cipher key, ciphers
- telegraphytelegraph, telegraphy, telegraph key, telegraph line, telegraph lines
- secret messagecipher, invisible ink, cryptogram, substitution cipher, Caesar cipher
- signalssignal, signals, signaling, sign, waved
tap codeplaintext
Unencoded readable information
Morse code · spoken language · written language · telephone call · public address
tap codepublic announcement
Official communication to all
broadcast · shouting · loudspeaker · megaphone · radio transmission
tap, taps, tapped, tapping, tapper, code, codes, coded, coding