unnerve (verb) - to cause to lose confidence, courage, or determination [uhn-nurv]
BREAKDOWN: UN- (opposite) + NERV- (nerve)
unnerving means disheartening, disconcerting, or creepy
unnerved means rendered anxious, fearful, or worried; distressed or disturbed
See also: enervate
“I see in the near future a crisis approaching that unnerves me and causes me to tremble for the safety of my country.” —Abraham Lincoln