The Collaborative International Dictionary of English v.0.48:

Wahoo \Wa*hoo"\, n.
   Any of various American trees or shrubs; specif.:
   (a) A certain shrub (Evonymus atropurpureus) having purple
       capsules which in dehiscence expose the scarlet-ariled
       seeds; -- called also burning bush.
   (b) Cascara buckthorn.
   (c) Basswood.
       [Webster 1913 Suppl.]