Webster's Revised Unabridged Dictionary · 1913

Disconcert

Disconcert , transitive verb

[Prefix dis- + concert: compare Old French desconcerter, French déconcerter.]

1.
To break up the harmonious progress of; to throw into disorder or confusion; as, the emperor disconcerted the plans of his enemy.
2.
To confuse the faculties of; to disturb the composure of; to discompose; to abash.
The embrace disconcerted the daughter-in-law somewhat, as the caresses of old gentlemen unshorn and perfumed with tobacco might well do. — Thackeray

Disconcert , noun

Want of concert; disagreement. — Sir W. Temple