defeatist

adjective

they were criticized for their defeatist attitude:

pessimistic, fatalistic, negative, resigned, cynical, discouraged, despondent, despairing, hopeless, bleak, gloomy, gloom-ridden, looking on the dark/black side.

▷antonyms optimistic, positive.

noun

pessimist, fatalist, yielder, cynic, prophet of doom, doomwatcher;

misery, killjoy, worrier, Job's comforter;

informal quitter, doom and gloom merchant, doomster, wet blanket.

▷antonyms optimist.

defeatist Oxford Dictionary of English