Definition of touch-powder in US English:

touch-powder

noun

rare, historical
  • Gunpowder placed in the pan of an early firearm to ignite the main charge after itself being ignited by friction, a spark, etc. Compare "priming powder".

Origin

Late 15th century. From touch + powder.

Pronunciation

touch-powder

/ˈtʌtʃˌpaʊdə/