confound

Etymology

From Middle English confounden (“destroy, ruin, perplex”), from Anglo-Norman cunfundre and Old French confondre, from Latin confundō (“to mingle, mix together”). Related to found (“to melt (metals in a foundry)”) (but not to found (“to start”), nor to find) and to fusion.

verb

1. To perplex or puzzle.
   And the brother of Jared being a large and mighty man, and a man highly favored of the Lord, Jared, his brother, said unto him: Cry unto the Lord, that he will not confound us that we may not understand our words. 1830, Joseph Smith, Jr., Book of Mormon: Ether, i, 34
   The fightback when it came was in the [Roger] Federer fashion: unfussy, filled with classy strokes from the back with perfectly timed interventions at the net that confounded his opponent. The third set passed in a bit of a blur, the fourth, which led to the second tie-break, was the most dramatic of the match. 29 June 2012, Kevin Mitchell, “Roger Federer back from Wimbledon 2012 brink to beat Julien Benneteau”, in The Guardian, archived from the original on 2016-11-15
2. To stun or amaze.
3. To fail to see the difference; to mix up; to confuse right and wrong.
   1651 (Latin edition 1642), Thomas Hobbes, De Cive (Latin title) Philosophicall Rudiments Concerning Government and Society (English), Hey who lesse seriously consider the force of words, doe sometimes confound Law with Counsell, sometimes with Covenant, sometimes with Right. They confound Law with Counsell, who think, that it is the duty of Monarchs not onely to give ear to their Counsellours, but also to obey them, as though it were in vaine to take Counsell, unlesse it were also followed.
4. (sometimes proscribed) To make something worse.
   Don't confound the situation by yelling.
   While she had obeyed him, smiling sweetly all the time, she had nursed a growing resentment of what she called his "Latin American macho attitude." To confound the problem, his mother, who lived with them on and off, was described by the wife as being as domineering as her son. 1983, Carol M. Anderson, Susan Stewart, Mastering Resistance: A Practical Guide to Family Therapy
5. To combine in a confused fashion; to mingle so as to make the parts indistinguishable.
   There the freſh and ſalt water would meete and be confounded together, […] 1611, Coryat, Crudities, volume I, page 195
6. To cause to be ashamed; to abash.
   His actions confounded the skeptics.
7. To defeat, to frustrate, to thwart.
   O Lord our God ariſe, / Scatter his enemies, / And make them fall: / Confound their politics, / Fruſtrate their knaviſh tricks, / On him our hopes we fix, / O ſave us all. a. 1745, unknown author, “God Save the King”, in The Gentleman's Magazine, volume 15, page 552
   1848 February 12, John Mitchel, The United Irishman, Letter to Lord Clarendon, I am now, in order the better to confound your politics, going to give you a true account of the means we intend to use, and of the rules, signs, and pass-words of our new United Irish Society Lodge A. 1.—They are so simple that you will never believe them.
8. (dated) To damn (a mild oath).
   Confound you!
   Confound the lady!
   "Number 43 is no better, Doctor," said the head-warder, in a slightly reproachful accent, looking in round the corner of my door. "Confound 43!" I responded from behind the pages of the Australian Sketcher. 1882, Arthur Conan Doyle, “My Friend the Murderer”, in The Gully of Bluemansdyke and Other Stories
9. (archaic) To destroy, ruin, or devastate; to bring to ruination.

noun

1. (statistics) A confounding variable.
   The participants certainly differ in how their practice is distributed (1, 2, or 3 days), but they also differ in how much total practice they get (3, 6, or 9 hours). This is a perfect example of a confound—it is impossible to tell if the results are due to one factor (distribution of practice) or the other (total practice hours); the two factors covary perfectly. 2009, C. James Goodwin, Research In Psychology: Methods and Design, John Wiley & Sons, page 175