| No. | Item | Definition |
|---|---|---|
| 1. | ack | message confirming receipt |
| 2. | acknowledgment | message showing receipt or recognition |
| 3. | advisory | official warning or notice |
| 4. | alarm | warning sound or alert |
| 5. | alert | warning or call for attention |
| 6. | announcement | public statement or notice |
| 7. | badge | mark showing status or role |
| 8. | beacon | guiding light or warning sign |
| 9. | beep | short electronic sound alert |
| 10. | bell | ringing sound as a signal |
| 11. | blink | brief light on and off |
| 12. | broadcast | message sent to many |
| 13. | bulletin | brief official announcement |
| 14. | buzz | vibrating or humming alert |
| 15. | call | request or summons to act |
| 16. | chime | pleasant alert sound |
| 17. | clue | piece of evidence or hint |
| 18. | communication | information exchanged or sent |
| 19. | communiqué | official message or announcement |
| 20. | cue | prompt that triggers a response |
| 21. | data | information sent or received |
| 22. | dispatch | message sent quickly |
| 23. | distress call | urgent request for help |
| 24. | DM | private direct message |
| 25. | downlink | transmission from a network |
| 26. | electronic written message | |
| 27. | emblem | symbol used to represent |
| 28. | evidence | information showing something is true |
| 29. | feed | stream of transmitted information |
| 30. | feedback | response giving evaluation |
| 31. | flag | sign used to draw attention |
| 32. | flare | bright signal or warning light |
| 33. | flash | brief burst of light |
| 34. | gesture | movement used to communicate |
| 35. | giveaway | clear revealing sign |
| 36. | glance | quick look used as a cue |
| 37. | go-ahead | permission or approval to proceed |
| 38. | green light | permission to proceed |
| 39. | hail | call to attract attention |
| 40. | handshake | exchange confirming connection |
| 41. | heads-up | advance warning or notice |
| 42. | hint | slight suggestion or clue |
| 43. | horn | loud sound used as warning |
| 44. | indication | something that points to a fact |
| 45. | indicator | thing that shows a condition |
| 46. | klaxon | loud harsh warning horn |
| 47. | knock | tap used to get attention |
| 48. | letter | written message sent to someone |
| 49. | light | visible signal used for guidance |
| 50. | locator | device that indicates position |
| 51. | look | expression used to communicate |
| 52. | mark | visible sign or trace |
| 53. | marker | sign that identifies or indicates |
| 54. | mayday | radio distress call |
| 55. | memo | brief internal message |
| 56. | message | information sent to someone |
| 57. | morse | coded dot-dash messaging |
| 58. | nod | head movement indicating agreement |
| 59. | note | short written message |
| 60. | notice | announcement or information given |
| 61. | notification | formal notice or alert |
| 62. | offer | proposal or indication of willingness |
| 63. | overture | approach indicating intent |
| 64. | ping | short electronic notification |
| 65. | pointer | thing that directs attention |
| 66. | post | public message shared online |
| 67. | prompt | stimulus that causes action |
| 68. | proof | evidence that confirms something |
| 69. | proposal | suggestion indicating a plan |
| 70. | radio call | message sent by radio |
| 71. | radio transmission | message sent over radio |
| 72. | reply | answer sent back |
| 73. | report | account or message about events |
| 74. | response | reply indicating reaction |
| 75. | ring | sound indicating a call |
| 76. | sign | indication or evidence of something |
| 77. | signifier | thing that indicates meaning |
| 78. | signpost | guide or indication of direction |
| 79. | siren | loud warning alarm |
| 80. | stimulus | something that provokes a response |
| 81. | symbol | thing representing an idea |
| 82. | symptom | sign of a condition |
| 83. | tap | light touch used as a cue |
| 84. | tell | revealing sign of something |
| 85. | tip-off | advance warning or clue |
| 86. | token | symbolic sign or indication |
| 87. | tone | audible alert sound |
| 88. | trace | small sign left behind |
| 89. | transmission | act of sending a message |
| 90. | trigger | thing that sets something off |
| 91. | update | new information or notice |
| 92. | uplink | transmission to a network |
| 93. | vibration | tactile alert from a device |
| 94. | warning | notice of possible danger |
| 95. | wave | hand motion used to indicate |
| 96. | whistle | sharp sound used to alert |
| 97. | wink | eye movement used as a cue |
| 98. | wire | telegram-style message |
| 99. | word | information or news conveyed |
| 100. | yell | loud call or shout |