Definition of hackthorn in US English:

hackthorn

noun

South African
rare
  • Any of several shrubs or small trees of southern Africa having hooked prickles, especially the densely spiny blackthorn, Acacia mellifera subsp. detinens.

Origin

Mid 19th century. From South African Dutch haakdoorn, with remodelling of the second element after thorn; the first element may perhaps partly reflect folk-etymological association with hack.

Pronunciation

hackthorn

/ˈhakθɔːn/