Source : Webster's Revised Unabridged Dictionary (1913)

Oxbow \Ox"bow`\, n.
   A frame of wood, bent into the shape of the letter U, and
   embracing an ox's neck as a kind of collar, the upper ends
   passing through the bar of the yoke; also, anything so
   shaped, as a bend in a river.

Source : WordNet®

oxbow
     n 1: the land inside an oxbow bend in a river
     2: a U-shaped curve in a stream
     3: a wooden framework bent in the shape of a U; its upper ends
        are attached to the horizontal yoke and the loop goes
        around the neck of an ox