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  27. 0-9
  1. 'ud
  2. u-2 affair
  3. u-boat
  4. u.s. news & world report
  5. uaxactún
  6. ugarit
  7. uí néill
  8. uighur
  9. uinta mountains
  10. ukiyo-e
  11. ukrainian language
  12. ukulele
  13. ulcer
  14. ulcerative colitis
  15. ulm, battle of
  16. ulster
  17. ulster cycle
  18. ultra
  19. ultrasonics
  20. ultrasound
  21. ultraviolet astronomy
  22. ultraviolet radiation
  23. uluru/ayers rock
  24. umayyad dynasty
  25. umbria
  26. umbrian
  27. umbrian language
  28. uncertainty principle
  29. uncle sam
  30. unconscious
  31. underground railroad
  32. unemployment
  33. unemployment insurance
  34. unesco
  35. uneven parallel bars
  36. ungava bay
  37. ungava peninsula
  38. ungulate
  39. unicef
  40. unicode
  41. unicorn
  42. unidentified flying object (ufo)
  43. unification church
  44. unified field theory
  45. unified science
  46. uniform circular motion
  47. uniformitarianism
  48. unilever
  49. union league
  50. union of soviet socialist republics (u.s.s.r.)
  51. union pacific corp.
  52. union shop
  53. union, act of
  54. unitarianism
  55. unité d'habitation
  56. united airlines
  57. united artists corp.
  58. united automobile workers (uaw)
  59. united fruit co.
  60. united kingdom of great britain and northern ireland
  61. united mine workers of america (umwa)
  62. united nations (un)
  63. united nations conference on trade and development (unctad)
  64. united nations development programme (undp)
  65. united nations general assembly
  66. united nations high commissioner for refugees, office of the (unhcr)
  67. united nations office for the coordination of humanitarian affairs (ocha)
  68. united nations relief and rehabilitation administration
  69. united nations resolution 242
  70. united nations secretariat
  71. united nations security council
  72. united nations trusteeship council
  73. united states air force (usaf)
  74. united states air force academy
  75. united states army
  76. united states coast guard
  77. united states courts of appeals
  78. united states district court
  79. united states marine corps (usmc)
  80. united states military academy
  81. united states steel corp.
  82. united states virgin islands
  83. united steelworkers (usw)
  84. unity (school of christianity)
  85. universal
  86. universal declaration of human rights
  87. universal negro improvement association (unia)
  88. universal pictures
  89. universal product code (upc)
  90. universal time
  91. universalism
  92. universe
  93. university
  94. unix
  95. unterwalden
  96. untouchable
  97. upanayana
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