The Pishon is the first of four rivers in Eden (the others are Gihon, Haddakel and Parat). Of the river Pishon it is said that it 'flows around the whole land of Havilah, where there is gold.'
The name Pishon comes from (push 1751, 1752) meaning spring about (1751), be scattered (1752). Klein gives besides a reference to the somewhat abstract `to spring about' the meaning to be strong, increase, spread. Another verb (Klein) spelled the same is to rest.
The name Pishon probably refers to a river that originates from a spring and forms into a delta. Jones reads Great Diffusion. NOBSE reads Freely Flowing.