The Collaborative International Dictionary of English v.0.48:

Chinquapin \Chin"qua*pin\, n. (Bot.)
   A branching, nut-bearing tree or shrub (Castanea pumila) of
   North America, from six to twenty feet high, allied to the
   chestnut. Also, its small, sweet, edible nat. [Written also
   chincapin and chinkapin.]
   [1913 Webster]

   Chinquapin oak, a small shrubby oak (Quercus prinoides)
      of the Atlantic States, with edible acorns.

   Western Chinquapin, an evergreen shrub or tree (Castanopes
      chrysophylla) of the Pacific coast. In California it is a
      shrub; in Oregon a tree 30 to 125 feet high.
      [1913 Webster]

WordNet (r) 3.0 (2006):

chinquapin
    n 1: shrubby tree closely related to the Allegheny chinkapin but
         with larger leaves; southern midwestern United States [syn:
         Ozark chinkapin, Ozark chinquapin, chinquapin,
         Castanea ozarkensis]
    2: shrubby chestnut tree of southeastern United States having
       small edible nuts [syn: Allegheny chinkapin, eastern
       chinquapin, chinquapin, dwarf chestnut, Castanea
       pumila]
    3: small nut of either of two small chestnut trees of the
       southern United States; resembles a hazelnut [syn:
       chincapin, chinkapin, chinquapin]