Definition of Irish Blackguard in English:

Irish Blackguard

noun

historical
  • A dark snuff made from charred tobacco, having the reputation of being particularly pungent and likely to cause sneezing.

    Irish blackguard is reputed to have been first produced in the late 18th century by a Dublin tobacconist and snuff-maker, Lundy Foot. It is now most commonly known as Irish High Toast.

Origin

Late 18th century; earliest use found in William Marshall (bap. 1745, d. 1818), agricultural writer and land agent.