A person who habitually expects the worst outcome or emphasizes negative aspects.
He's a pessimist, so he always expects bad outcomes.
Opposite: an optimist, someone who expects favorable outcomes.
Adjectival form meaning 'pessimistic', used to describe a viewpoint or attitude rather than a person.
Compound of 悲観 (pessimism) + 論者 (proponent, advocate). 悲観 is from 悲 (sad) + 観 (view).