Definition of "blackstrap"

blackstrap

noun
usually uncountable, plural blackstraps
1. The dark, viscous molasses remaining after maximum extraction of sugar from raw sugar cane, used in manufacturing and cattle feed.
  Quotations
  Smoked over cherry and mesquite wood, and dried in a convection oven, it gets its flavors from organic blackstrap molasses, Jim Beam bourbon, and salt and pepper.
  2007 July 25, David Hochman, “For Epicures, a New Take on Jerky”, in New York Times‎
2. (obsolete) A mixture of spirituous liquor (usually rum) and molasses.
  Quotations
  No blackstrap to-night; switchel, or ginger pop.
  1845, Sylvester Judd, Margaret: A Tale of the Real and the Ideal, Blight and Bloom; Including Sketches of a Place Not Before Described, Called Mons Christi
3. (obsolete, nautical, slang) Bad port wine; any common wine of the Mediterranean.