Source : Webster's Revised Unabridged Dictionary (1913)

Christ's-thorn \Christ's-thorn`\, n. (Bot.)
   One of several prickly or thorny shrubs found in Palestine,
   especially the {Paliurus aculeatus}, {Zizyphus
   Spina-Christi}, and {Z. vulgaris}. The last bears the fruit
   called jujube, and may be considered to have been the most
   readily obtainable for the Crown of Thorns.