One word Substitution 1

51. That which cannot be avoided

Inevitable

52. A position for which no salary is paid

Honorary

53. That which cannot be defended

Indefensible

54. Practice of having several wives

Polygamy

55. Practice of having several husbands

Polyandry

56. Practice of having one wife or husband

Monogamy

57. Practice of having two wives or husbands

Bigamy

58. That which is not likely to happen

Improbable

59. People living at the same time

Contemporaries

60. A book published after the death of its author

Posthumas

61. A book written by an unknown author

Anonymous

62. A life history written by oneself

Autobiography

63. A life history written by somebody else

Biography

64. People who work together

Colleagues

65. One who eats too much

Glutton

66. That which cannot be satisfied

Insatiable

67. One who questions everything

Cynic

68. A flesh eating animal

Carnivorous

69. A grass eating animal

Herbivorous

70. One who lives in a foreign country

Immigrant

71. To transfer one's authority to another

Delegate

72. One who is a newcomer

Neophyte

73. That which is lawful

Legal

74. That which is against law

Illegal

75. One who is unmarried

Celibate

76. A game in which no one wins

Draw

77. A study of man

Anthropology

78. A study of races

Ethnology

79. A study of the body

Physiology

80. A study of animals

Zoology

81. A study of birds

Ornithology

82. A study of ancient things

Archaeology

83. A study of derivation of words

Etymology

84. Murder of a human being

Homicide

85. Murder of a father

Patricide

86. Murder of a mother

Matricide

87. Murder of an brother

Fratricide

88. Murder of an infant

Infanticide

89. Murder of self

Suicide

90. Murder of the king

Regicide

91. To free somebody from all blame

Exonerate

92. To write under a different name

Pseudonym

93. A thing no longer in use

Obsolete

94. A handwriting that cannot be read

Illegible

95. Words written on the tomb of a person

Epitaph

96. One who is greedy for money

Avaricious

97. Something that cannot be imitated

Inimitable

98. One who doesn't know how to read and write

Illiterate

99. A person's peculiar habit Idiosyncrasy

100. An animal who preys on other animals

Predator

101. Violating the sanctity of a church

Sacrilege

102. One who can throw his voice

Ventriloquist

One word Substitution

1. One who is out to subvert a government 

Anarchist

2. One who is recovering from illness 

Convalescent

3. One who is all powerful 

Omnipotent

4. One who is present everywhere 

Omnipresent

5. One who knows everything 

Omniscient

6. One who is easily deceived 

Gullible

7. One who does not make mistakes 

Infallible

8. One who can do anything for money 

Mercenary

9. One who has no money 

Pauper

10. One who changes sides 

Turncoat

11. One who works for free 

Volunteer

12. One who loves books 

Bibliophile

13. One who can speak two languages 

Bilingual

14. One who loves mankind 

Philanthropist

15. One who hates mankind 

Misanthrope

16. One who looks on the bright side of things 

Optimist

17. One who looks on the dark side of things 

Pessimist

18. One who doubts the existence of god 

Agnostic

19. One who pretends to be what he is not 

Hypocrite

20. One incapable of being tired 

Indefatigable

21. One who helps others Good 

Samaritan

22. One who copies from other writers 

Plagiarist

23. One who hates women 

Misogynist

24. One who knows many languages 

Polyglot

25. One who is fond of sensuous pleasures 

Epicure

26. One who thinks only of himself 

Egoist

27. One who thinks only of welfare of women 

Feminist.

28. One who is indifferent to pleasure or pain 

Stoic

29. One who is quite like a woman 

Effeminate

30. One who has strange habits 

Eccentric

31. One who speaks less 

Reticent

32. One who goes on foot 

Pedestrian

33. One who believes in fate 

Fatalist

34. One who dies without a Will 

Intestate

35. One who always thinks himself to be ill 

Valetudinarian

36. A Government by the people 

Democracy

37. A Government by a king or queen 

Monarchy

38. A Government by the officials 

Bureaucracy

39. A Government by the rich 

Plutocracy

40. A Government by the few 

Oligarchy

41. A Government by the Nobles 

Aristocracy

42. A Government by one 

Autocracy

43. Rule by the mob 

Mobocracy

44. That through which light can pass 

Transparent

45. That through which light cannot pass 

Opaque

46. That through which light can partly pass 

Translucent

47. A sentence whose meaning is unclear 

Ambiguous

48. A place where orphans live 

Orphanage

49. That which cannot be described 

Indescribable

50. That which cannot be imitated 

Inimitable

Even More...