UNNERVE
faze, unnerve, enervate, unsettle
(verb) disturb the composure of
Source: WordNet® 3.1
Etymology
Verb
unnerve (third-person singular simple present unnerves, present participle unnerving, simple past and past participle unnerved)
To deprive of nerve, force, or strength; to weaken; to enfeeble.
To make somebody nervous, upset, alarm, shake the resolve of.
Source: Wiktionary
Un*nerve", v. t. Etym: [1st pref. un- + nerve.]
Definition: To deprive of nerve, force, or strength; to weaken; to
enfeeble; as, to unnerve the arm.
Unequal match'd, . . . The unnerved father falls. Shak.
Source: Webster’s Unabridged Dictionary 1913 Edition