WordNet (r) 3.0 (2006):

black locust
    n 1: strong stiff wood of a black-locust tree; very resistant to
         decay
    2: large thorny tree of eastern and central United States having
       pinnately compound leaves and drooping racemes of white
       flowers; widely naturalized in many varieties in temperate
       regions [syn: black locust, yellow locust, Robinia
       pseudoacacia]