Dictionary.com/discomfit (etymology):

discomfit (dis-KUHM-fit; dis-kuhm-FIT) transitive verb

1. To make uneasy or perplexed; disconcert. See Synonyms at embarrass.
2. To thwart the plans of; frustrate.
3. Archaic. To defeat in battle; vanquish.

Source: The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2000 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.

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v : cause to lose one's composure [syn: upset, discompose, untune, disconcert]

Source: WordNet ® 2.0, © 2003 Princeton University