nihilism: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
existentialism:a chiefly 20th century philosophical movement embracing diverse doctrines but centering on analysis of individual existence in an unfathomable universe and the plight of the individual who must assume ultimate responsibility for acts of free will without any certain knowledge of what is right or wrong or good or bad
is the philosophical theory that life has no intrinsic meaning or value. With respect to the universe, existential nihilism posits that a single human or even the entire human species is insignificant, without purpose and unlikely to change in the totality of existence. According to the theory, each individual is an isolated being “thrown” into the universe, barred from knowing “why”, yet compelled to invent meaning. The inherent meaninglessness of life is largely explored in the philosophical school of existentialism, where one can potentially create his or her own subjective “meaning” or “purpose”. Of all types of nihilism, existential nihilism gets the most literary and philosophical attention.