verb
unnerve implies a causing to lose courage or self-control as by shocking, dismaying, etc. the screams unnerved her; enervate implies a gradual loss of strength or vitality, as because of climate, indolence, etc. enervating heat; unman implies a loss of manly courage, fortitude, or spirit he was so unmanned by the news that he broke into tears
See unnerve in Webster's New World Roget's A-Z Thesaurus II
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