Full Definition of nihilism
1
a : a viewpoint that traditional values and beliefs are unfounded and that existence is senseless and useless
b : a doctrine that denies any objective ground of truth and especially of moral truths
2
a : a doctrine or belief that conditions in the social organization are so bad as to make destruction desirable for its own sake independent of any constructive program or possibility
b capitalized : the program of a 19th century Russian party advocating revolutionary reform and using terrorism and assassination