locust tree \lo"cust tree`\n. etymol. uncertain. bot.
   a large north american tree of the genus robinia robinia
   pseudacacia, producing large slender racemes of white,
   fragrant, papilionaceous flowers, and often cultivated as an
   ornamental tree. in england it is called acacia.
   1913 webster

   note: the name is also applied to other trees of different
         genera, especially to those of the genus hymenaea,
         of which hymenaea courbaril is a lofty, spreading
         tree of south america; also to the carob tree
         ceratonia siliqua, a tree growing in the
         mediterranean region.
         1913 webster

   honey locust tree bot., a tree of the genus gleditschia
       gleditschia triacanthus, having pinnate leaves and
      strong branching thorns; -- so called from a sweet pulp
      found between the seeds in the pods. called also simply
      honey locust.

   water locust tree bot., a small swamp tree gleditschia
      monosperma, of the southern united states.
      1913 webster
see also:
robinia robinia pseudacacia acacia hymenaea hymenaea courbaril ceratonia siliqua 
honey locust tree gleditschia gleditschia triacanthus honey locust water locust tree 
gleditschia monosperma 

water locust \wa"ter lo"cust\ bot.
   a thorny leguminous tree gleditschia monosperma which
   grows in the swamps of the mississippi valley.
   1913 webster
see also:
gleditschia monosperma