| No. | Item | Definition |
|---|---|---|
| 1. | a dirty little secret | shameful hidden secret |
| 2. | a guarded secret | carefully protected secret |
| 3. | a secret weapon | hidden advantage |
| 4. | a skeleton in the closet | a hidden shameful secret |
| 5. | a snake in the grass | hidden treacherous person |
| 6. | a well-kept secret | kept from public knowledge |
| 7. | a wolf in sheep’s clothing | dangerous person pretending harmless |
| 8. | air dirty laundry | reveal private problems |
| 9. | bare your soul | reveal private feelings |
| 10. | be in on it | share the secret |
| 11. | be privy to | have secret knowledge |
| 12. | behind closed doors | in private |
| 13. | behind the scenes | out of public view |
| 14. | between ourselves | keep it private |
| 15. | between you and me | keep it private |
| 16. | bite your tongue | avoid saying something |
| 17. | blurt it out | say it suddenly |
| 18. | button your lip | stop talking |
| 19. | clam up | become silent |
| 20. | cloak-and-dagger | secretive and mysterious |
| 21. | close-mouthed | not revealing information |
| 22. | come clean | admit the truth |
| 23. | cover your tracks | hide evidence |
| 24. | die with the secret | never reveal it |
| 25. | double-cross | betray deceitfully |
| 26. | drop a hint | suggest indirectly |
| 27. | fess up | confess |
| 28. | fly under the radar | avoid notice |
| 29. | get it off your chest | confess something |
| 30. | give the game away | reveal the secret plan |
| 31. | hold your tongue | stop yourself speaking |
| 32. | hush-hush | kept secret |
| 33. | in camera | in private, not public |
| 34. | in the shadows | out of public view |
| 35. | in your back pocket | kept in reserve secretly |
| 36. | inside information | confidential information |
| 37. | inside scoop | secret information |
| 38. | keep a lid on it | keep it quiet |
| 39. | keep it close to the vest | keep plans secret |
| 40. | keep it hush-hush | keep it secret |
| 41. | keep it in the family | share only with family |
| 42. | keep it on the down-low | keep it discreet |
| 43. | keep it to yourself | don’t tell others |
| 44. | keep it under your hat | keep it secret |
| 45. | keep your cards close | hide your intentions |
| 46. | keep your counsel | keep your opinion private |
| 47. | keep your mouth shut | stay silent |
| 48. | leave no trace | avoid being detected |
| 49. | let someone in on | share a secret |
| 50. | let the cat out of the bag | reveal a secret accidentally |
| 51. | lie low | stay hidden |
| 52. | lift the veil | reveal the truth |
| 53. | listen in | secretly overhear |
| 54. | little pitchers have big ears | children may overhear |
| 55. | loose lips sink ships | talking can cause trouble |
| 56. | make a clean breast of it | confess fully |
| 57. | mum’s the word | stay silent about it |
| 58. | need-to-know basis | shared only when necessary |
| 59. | not breathe a word | say nothing about it |
| 60. | not say a peep | stay completely silent |
| 61. | not tell a soul | tell nobody |
| 62. | not utter a word | say nothing |
| 63. | off the record | not for public reporting |
| 64. | on the QT | secretly |
| 65. | own up | admit responsibility |
| 66. | paper over the cracks | hide flaws |
| 67. | peek behind the curtain | see hidden workings |
| 68. | play it close to the vest | act secretively |
| 69. | play your cards close | hide your intentions |
| 70. | poker face | expressionless face |
| 71. | pull back the curtain | reveal what was hidden |
| 72. | put a sock in it | stop talking |
| 73. | put your foot in it | say something embarrassing |
| 74. | rat someone out | betray by informing |
| 75. | read someone in | brief someone privately |
| 76. | seal your lips | promise silence |
| 77. | shoot your mouth off | talk too much |
| 78. | sing like a canary | inform on others |
| 79. | smoke and mirrors | deceptive concealment |
| 80. | speak out of turn | say something inappropriate |
| 81. | spill the beans | reveal a secret |
| 82. | spill your guts | reveal everything |
| 83. | sweep it under the rug | hide a problem |
| 84. | take it to the grave | never reveal it |
| 85. | tattle on someone | inform on someone |
| 86. | tell tales | report others’ secrets |
| 87. | the best-kept secret | little-known excellent thing |
| 88. | the lowdown | the real details |
| 89. | the naked truth | the plain truth |
| 90. | the skinny | the real details |
| 91. | tight-lipped | unwilling to speak |
| 92. | ulterior motive | hidden reason |
| 93. | under lock and key | securely locked away |
| 94. | under the cloak of night | secretly at night |
| 95. | under the counter | secretly, unofficially |
| 96. | under wraps | kept secret |
| 97. | wash dirty linen in public | reveal private problems publicly |
| 98. | whisper campaign | secret rumor spreading |
| 99. | wipe the slate clean | erase past wrongdoing |
| 100. | zip your lip | keep quiet |
