tr.v. dis·con·cert·ed, dis·con·cert·ing, dis·con·certs
1. To cause to lose composure; embarrass or confuse: He was disconcerted by the teacher's angry tone. See Synonyms at embarrass.
2. To frustrate (plans, for example) by throwing into disorder; disarrange.
[Obsolete French disconcerter, from Old French desconcerter : des-, dis- + concerter, to bring into agreement (from Old Italian concertare; see CONCERT).]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.
American Heritage Dictionary Products
The American Heritage Dictionary, 5th Edition
The American Heritage Dictionary of Idioms
The American Heritage Roget's Thesaurus
Curious George's Dictionary
The American Heritage Children's Dictionary
The American Heritage Dictionary of Indo-European Roots
The American Heritage Student Grammar Dictionary
The American Heritage Desk Dictionary + Thesaurus
The American Heritage Science Dictionary
The American Heritage Dictionary of Business Terms
The American Heritage Student Dictionary
The American Heritage Essential Student Thesaurus