| No. | Item | Definition |
|---|---|---|
| 1. | anonymous | Having an unknown identity. |
| 2. | back-channel | Using unofficial secret communication. |
| 3. | backroom | Secretive and unofficial. |
| 4. | backstage | Behind the public presentation. |
| 5. | behind a veil | Partly hidden or disguised. |
| 6. | behind closed doors | Done privately, not publicly. |
| 7. | behind-the-scenes | Happening out of public view. |
| 8. | below the radar | Avoiding notice or scrutiny. |
| 9. | beneath the surface | Hidden from obvious view. |
| 10. | black | Secret, especially military or intelligence. |
| 11. | buried | Hidden or suppressed. |
| 12. | camouflaged | Hidden by blending with surroundings. |
| 13. | clandestine | Done secretly, often illicitly. |
| 14. | classified | Officially restricted from public access. |
| 15. | cloak-and-dagger | Involving secrecy and intrigue. |
| 16. | closed | Not open to outsiders. |
| 17. | closemouthed | Unwilling to reveal information. |
| 18. | closeted | Kept hidden or private. |
| 19. | concealed | Hidden from view or knowledge. |
| 20. | confidential | Meant to be kept secret. |
| 21. | covered | Hidden or protected from view. |
| 22. | dark | Hidden from clear view. |
| 23. | discreet | Careful to avoid attention. |
| 24. | disguised | Made to appear as something else. |
| 25. | embedded | Placed secretly within a group. |
| 26. | encrypted | Converted into unreadable secret form. |
| 27. | exclusive | Limited to a select group. |
| 28. | eyes-only | Restricted to specified readers. |
| 29. | furtive | Secretive and sly in manner. |
| 30. | guarded | Careful not to reveal much. |
| 31. | hermetic | Sealed off or secretive. |
| 32. | hidden | Kept out of sight or notice. |
| 33. | hush-hush | Kept very secret. |
| 34. | hushed-up | Kept quiet to avoid exposure. |
| 35. | in confidence | Shared with expected secrecy. |
| 36. | in private | Done away from public attention. |
| 37. | in secret | Done without others knowing. |
| 38. | in-house | Kept within an organization. |
| 39. | incognito | Using a hidden identity. |
| 40. | inconspicuous | Not easily noticed. |
| 41. | indirect | Not openly stated or done. |
| 42. | insider | Known only within a group. |
| 43. | internal | Kept within an organization. |
| 44. | invisible | Impossible or hard to see. |
| 45. | kept hidden | Maintained out of sight. |
| 46. | kept quiet | Not allowed to become public. |
| 47. | kept secret | Not shared with others. |
| 48. | low-key | Not attracting much attention. |
| 49. | low-profile | Avoiding public attention. |
| 50. | masked | Hidden behind a false appearance. |
| 51. | murky | Unclear or suspiciously secret. |
| 52. | need-to-know | Limited to necessary recipients. |
| 53. | nonpublic | Not available to the public. |
| 54. | obscure | Not clearly seen or known. |
| 55. | off-the-record | Not for public disclosure. |
| 56. | offscreen | Away from public view or attention. |
| 57. | on the down-low | Kept informal and secret. |
| 58. | on the quiet | Done secretly and discreetly. |
| 59. | on the sly | Done secretly or sneakily. |
| 60. | opaque | Not transparent or easily understood. |
| 61. | out of public view | Not visible to the public. |
| 62. | out of sight | Hidden from view. |
| 63. | out of view | Not visible. |
| 64. | plainclothes | Wearing ordinary clothes secretly. |
| 65. | private | Not open or known publicly. |
| 66. | privileged | Restricted to certain people. |
| 67. | pseudonymous | Using a false name. |
| 68. | restricted | Limited to authorized people only. |
| 69. | reticent | Reserved about revealing information. |
| 70. | screened | Hidden or protected from view. |
| 71. | secret | Kept from public knowledge. |
| 72. | sensitive | Requiring careful confidential handling. |
| 73. | shadowy | Mysterious and secretive. |
| 74. | shrouded | Covered or hidden from view. |
| 75. | sly | Secretive and crafty. |
| 76. | sneaky | Secretive in a dishonest way. |
| 77. | stealth | Done with secrecy and concealment. |
| 78. | stealthy | Moving or acting secretly. |
| 79. | sub rosa | Done in strict secrecy. |
| 80. | surreptitious | Done secretly to avoid notice. |
| 81. | tight-lipped | Refusing to speak openly. |
| 82. | top-secret | Of the highest secrecy level. |
| 83. | under cover | Hidden or operating secretly. |
| 84. | under the radar | Avoiding notice or attention. |
| 85. | under wraps | Kept secret until revealed. |
| 86. | under-the-table | Secret and often dishonest. |
| 87. | undercover | Operating secretly to gather information. |
| 88. | underground | Operating secretly, often against authority. |
| 89. | underhand | Secret and dishonest. |
| 90. | underhanded | Secret and unfair. |
| 91. | undetected | Not discovered or identified. |
| 92. | undisclosed | Not revealed to others. |
| 93. | undocumented | Not officially recorded or disclosed. |
| 94. | unnoticed | Not attracting attention. |
| 95. | unobserved | Not watched or noticed. |
| 96. | unpublicized | Not announced or advertised publicly. |
| 97. | unpublished | Not made publicly available. |
| 98. | unrevealed | Not made known. |
| 99. | unseen | Not seen or noticed. |
| 100. | veiled | Indirectly or partly hidden. |

