Disconcert is defined as to embarrass or frustrate.(verb)
An example of disconcert is for a person to upset her best friend by telling her secret to everyone.
See disconcert in Webster's New World College Dictionary
Origin: OFr desconcerter: see dis- & concert
See disconcert in American Heritage Dictionary 4
transitive verb dis·con·cert·ed, dis·con·cert·ing, dis·con·certs
Origin: Obsolete French disconcerter
Origin: , from Old French desconcerter
Origin: : des-, dis-
Origin: + concerter, to bring into agreement (from Old Italian concertare; see concert).
Learn more about disconcert