(archaic) A worthless mixture, especially of liquors.
1637, John Taylor, Drinke and Welcome, London: Anne Griffin, “Beere,”
Indeede Beere, by a Mixture of Wine, it enjoyes approbation amongst some few (that hardly understand wherefore) but then it is no longer Beere, but hath lost both Name and Nature, and is called Balderdash (an Utopian denomination) …
1783, John O’Keeffe, The Agreeable Surprise, Newry: R. Stevenson, Act I, Scene 1, pp. 6-7,
… I took him to oblige a foolish old friend of mine, who intended him for Saint Omers; so I must keep him to draw good wine, and brew balderdash Latin.