| No. | Item | Definition |
|---|---|---|
| 1. | alias | assumed name to conceal identity |
| 2. | anonymous | with identity kept hidden |
| 3. | arcane | known by few; obscure |
| 4. | back-channel | private route for communication |
| 5. | backdoor | hidden way in or around rules |
| 6. | backroom | done privately, not openly |
| 7. | behind closed doors | in private, not publicly |
| 8. | between us | kept only between two people |
| 9. | buried | hidden so it is hard to find |
| 10. | cagey | reluctant to share details |
| 11. | ciphered | encoded to conceal meaning |
| 12. | clandestine | kept secret, often illicitly |
| 13. | classified | officially kept from public view |
| 14. | close to the vest | kept private and not shared |
| 15. | close-mouthed | not revealing information |
| 16. | closely guarded | protected from being revealed |
| 17. | closely held | known by very few |
| 18. | coded | written to hide meaning |
| 19. | concealed | hidden from view or knowledge |
| 20. | confidential | meant to be kept private |
| 21. | covert | done or kept out of view |
| 22. | cryptic | hard to understand; secretive |
| 23. | discreet | careful to avoid being noticed |
| 24. | discreetly kept | kept private with care |
| 25. | disguised | made to look different; hidden |
| 26. | encrypted | protected by secret code |
| 27. | enigmatic | mysterious and hard to know |
| 28. | esoteric | understood by a small group |
| 29. | for your eyes only | intended for one person only |
| 30. | furtive | secretive and trying not to be seen |
| 31. | guarded | carefully protected from disclosure |
| 32. | hidden | kept out of sight or knowledge |
| 33. | highly confidential | very strictly kept private |
| 34. | hush-hush | kept very quiet and private |
| 35. | in code | expressed using a secret code |
| 36. | in confidence | shared privately and trusted |
| 37. | in hiding | kept hidden from others |
| 38. | in the dark | kept from knowing |
| 39. | in the shadows | kept hidden and unseen |
| 40. | incognito | with identity concealed |
| 41. | internal | meant only for insiders |
| 42. | invisible | not seen or easily detected |
| 43. | kept in-house | kept within an organization |
| 44. | kept private | not shared with others |
| 45. | kept quiet | not talked about publicly |
| 46. | latent | present but not visible |
| 47. | locked away | kept secured and hidden |
| 48. | locked down | strictly controlled and hidden |
| 49. | low-profile | kept from public attention |
| 50. | masked | covered to hide the truth |
| 51. | mum | silent; not revealing anything |
| 52. | mysterious | not easily explained or known |
| 53. | need-to-know | shared only when necessary |
| 54. | non-disclosed | not revealed to others |
| 55. | nonpublic | not available to the public |
| 56. | not for publication | not to be made public |
| 57. | obscured | made hard to see or know |
| 58. | occult | hidden or secretive in nature |
| 59. | off the record | not for public disclosure |
| 60. | off-limits | not allowed to be accessed |
| 61. | on the QT | quietly and secretly |
| 62. | on the sly | in a secretive way |
| 63. | out of sight | not visible; kept hidden |
| 64. | out of view | not visible to others |
| 65. | private | not for others to know |
| 66. | privileged | restricted to certain people |
| 67. | proprietary | owned and kept from others |
| 68. | protected | kept safe from disclosure |
| 69. | quiet | kept from public attention |
| 70. | redacted | partly hidden by removing details |
| 71. | restricted | limited to authorized people |
| 72. | reticent | not revealing much |
| 73. | sealed | closed off from access |
| 74. | secrecy | state of being kept hidden |
| 75. | secretive | inclined to keep things hidden |
| 76. | sensitive | requiring careful confidentiality |
| 77. | shrouded | covered and kept from view |
| 78. | smokescreen | something hiding the real truth |
| 79. | stealthy | quietly hidden to avoid detection |
| 80. | sub rosa | in secret; confidentially |
| 81. | suppressed | kept from being revealed |
| 82. | surreptitious | done secretly to avoid notice |
| 83. | tight-lipped | not willing to reveal |
| 84. | unacknowledged | not openly admitted |
| 85. | unavowed | not openly declared |
| 86. | under a veil | kept hidden from view |
| 87. | under cover | hidden from public view |
| 88. | under lock and key | securely kept and inaccessible |
| 89. | under seal | officially kept from disclosure |
| 90. | under the radar | not noticed or detected |
| 91. | under the table | done secretly, often improperly |
| 92. | underground | hidden from official view |
| 93. | undisclosed | not revealed or made known |
| 94. | unlisted | not publicly recorded or shown |
| 95. | unpublicized | not made public |
| 96. | unpublished | not released to the public |
| 97. | unrevealed | not yet made known |
| 98. | untraceable | cannot be tracked or found |
| 99. | veiled | partly hidden or obscured |
| 100. | withheld | not given or revealed |