confound

To confound is defined as to confuse someone, defeat an enemy or foil a plan.

(verb)

An example of confound is when you ask someone a really tough question.
An example of confound is when you act in a suprising way, leaving friends confused about your behavior.
An example of confound is when you stop a plot to overthrow the government.

See confound in Webster's New World College Dictionary

transitive verb

Origin: ME confouṅden < OFr confondre < L confundere, to pour together, confuse < com-, together + fundere, to pour: see found

See confound in American Heritage Dictionary 4

transitive verb con·found·ed, con·found·ing, con·founds

To cause to become confused or perplexed. See Synonyms at puzzle.
To fail to distinguish; mix up: confound fiction and fact.
To make (something bad) worse: Do not confound the problem by losing your temper.
To cause to be ashamed; abash: an invention that confounded the skeptics.
To damn.
a. To frustrate: trivial demands that confounded the peace talks.
b. Archaic To bring to ruination.