an Old World spiny shrub (Paliurus spina-christi) of the buckthorn family, supposed to have been used for Christ's crown of thorns
See Christ's-thorn in American Heritage Dictionary 4
(krīsts) also Christ-thorn(krīstˈthôrnˌ)
noun
Either of two similar and related Old World spiny shrubs (Ziziphus spina-christi or Paliurus spina-christi) popularly believed to have been used for Jesus's crown of thorns.
Any of several other plants, such as the crown-of-thorns.