Source : Webster's Revised Unabridged Dictionary (1913)

Bur fish \Bur" fish`\ (Zo["o]l.)
   A spinose, plectognath fish of the Allantic coast of the
   United States (esp. {Chilo mycterus geometricus}) having the
   power of distending its body with water or air, so as to
   resemble a chestnut bur; -- called also {ball fish}, {balloon
   fish}, and {swellfish}.