Webster's Revised Unabridged Dictionary · 1913

Pessimist

Pessimist , noun

[Latin pessimus worst: compare French pessimiste.]

1.
(Metaphysics) One who advocates the doctrine of pessimism; -- opposed to optimist.
2.
One who looks on the dark side of things.

Pessimist , adjective

(Metaphysics) Of or pertaining to pessimism; characterized by pessimism; gloomy; foreboding.
Giving utterance to pessimistic doubt. — Encyc. Brit

Also: Pessimistic