Spark  —n. 1 fiery particle thrown from a fire, alight in ashes, or produced by a flint, match, etc. 2 (often foll. By of) small amount (spark of interest). 3  a flash of light between electric conductors etc. B this serving to ignite the explosive mixture in an internal-combustion engine. 4 a flash of wit etc. B (also bright spark) witty or lively person. —v. 1 emit a spark or sparks. 2 (often foll. By off) stir into activity; initiate.  sparky adj. [old english]