existent: something of existing
-ial: of doing something
-ism: the ism of something
So existentialism means:
The ism of something of existing.
It means "the belief in philosophy that people are responsible for their own actions and experiences, and that the world has no meaning". And in other words, it means "we are just the tools with which the natural law can fulfill its will", our existence is meaningless for ourself, but is meaningful for the natural law.
Evolution of usage
The question of the ism of existent has perplexed many philosophers.
The question of the existential ism has perplexed many philosophers.
The question of existentialism has perplexed many philosophers.