noun
A person who believes that all events are predetermined and inevitable.
彼は宿命論者だから、努力しても無駄だと思っている。
He is a fatalist, so he thinks effort is futile.
宿命論 is the doctrine of fatalism, while 宿命論者 refers to a person who holds that belief.
Compound of 宿命 (fate) + 論 (theory) + 者 (person). The exact historical derivation is uncertain; the spelling is conventionally associated with the meaning.