| No. | Item | Definition |
|---|---|---|
| 1. | access code | code permitting entry or use |
| 2. | anchor | main support or stabilizer |
| 3. | answer | solution to a question |
| 4. | authenticator | tool confirming identity |
| 5. | authorization | official permission to access |
| 6. | axis | central line or principle |
| 7. | backbone | chief support or strength |
| 8. | badge | identification granting access |
| 9. | base | supporting foundation |
| 10. | basic | forming an essential foundation |
| 11. | basis | foundation or starting point |
| 12. | bedrock | firm basic foundation |
| 13. | center | most important point or part |
| 14. | centerpiece | main or most noticeable feature |
| 15. | central | most important or main |
| 16. | chief | highest in importance |
| 17. | core | central and most important |
| 18. | cornerstone | essential foundation or element |
| 19. | critical | of decisive importance |
| 20. | crucial | extremely important or necessary |
| 21. | crux | most important point |
| 22. | decisive | settling or determining an outcome |
| 23. | determinant | factor deciding an outcome |
| 24. | dominant | most influential or important |
| 25. | door opener | thing that opens a door |
| 26. | driver | main force behind something |
| 27. | element | necessary part of something |
| 28. | engine | driving force or source |
| 29. | entry pass | document allowing admission |
| 30. | essence | most important nature |
| 31. | essential | absolutely necessary |
| 32. | explanation | statement making something clear |
| 33. | factor | influential element in a result |
| 34. | focal point | main center of attention |
| 35. | focus | center of attention or effort |
| 36. | foremost | most important or prominent |
| 37. | foundation | underlying base or support |
| 38. | foundational | serving as a necessary base |
| 39. | fulcrum | main support or turning point |
| 40. | fundamental | basic and essential |
| 41. | gist | main point or meaning |
| 42. | glossary | list explaining terms |
| 43. | heart | central or most important part |
| 44. | hinge | decisive point or factor |
| 45. | hub | central point of activity |
| 46. | ID | proof of identity |
| 47. | identity card | card proving identity |
| 48. | imperative | urgent necessity or requirement |
| 49. | important | having great significance |
| 50. | indispensable | impossible to do without |
| 51. | ingredient | component needed for a result |
| 52. | interpretation | meaning assigned to something |
| 53. | kernel | central or essential part |
| 54. | keycard | card used to open doors |
| 55. | keystone | central supporting element |
| 56. | leading | most important or prominent |
| 57. | legend | guide explaining symbols on a map |
| 58. | license | official permission to do something |
| 59. | linchpin | thing holding everything together |
| 60. | main | chief or most important |
| 61. | major | very important or significant |
| 62. | map legend | map guide explaining symbols |
| 63. | meaning | what something signifies |
| 64. | meat | substantial or important part |
| 65. | mode | type of musical scale |
| 66. | must | something necessary or required |
| 67. | necessary | needed or required |
| 68. | necessity | something that is needed |
| 69. | nub | central point of a matter |
| 70. | nucleus | central part or core |
| 71. | opener | tool or means for opening |
| 72. | paramount | more important than all others |
| 73. | pillar | strong essential support |
| 74. | pith | essential part or meaning |
| 75. | pivot | central turning point |
| 76. | pivotal | vitally important to outcomes |
| 77. | point | main idea or purpose |
| 78. | primary | first in importance |
| 79. | prime | first in importance |
| 80. | principal | most important or leading |
| 81. | remote | device controlling something at distance |
| 82. | requirement | something needed or demanded |
| 83. | requisite | necessary thing or condition |
| 84. | root | basic source or cause |
| 85. | secret | hidden means of success |
| 86. | sense | intended meaning or interpretation |
| 87. | significant | notably important or meaningful |
| 88. | sine qua non | essential condition or requirement |
| 89. | solution | answer to a problem |
| 90. | soul | essential spirit or part |
| 91. | substance | essential meaning or content |
| 92. | supreme | highest in importance or rank |
| 93. | ticket | proof allowing entry |
| 94. | token | device or sign granting access |
| 95. | tonality | musical system centered on a note |
| 96. | transponder | device sending an identifying signal |
| 97. | underlying | basic and hidden beneath |
| 98. | unlock code | code that opens access |
| 99. | unlocker | Something that opens access. |
| 100. | vital | needed for success or life |
