A cudgel of oak, blackthorn, or other hardwood.
A club or cudgel.
Origin of shillelagh
- After Shillelagh , a village of east-central Ireland where cudgels were made with wood from the formerly extensive local oak forests
From American Heritage Dictionary of the English Language, 5th Edition
- Either from Shillelagh, County Wicklow, in Ireland (from Irish Síol (“descendants") Éalaigh (a name)), because the forest near it provided the wood from which such clubs were made, or from sail (“cudgel") + éille (“thong").