A vocabulary of landscape — a landscape of words 1083 entries

anabranch

AN-uh-branch
A channel that leaves a river and rejoins it downstream, enclosing an island between the two. Anabranching rivers carry several stable, vegetated channels at once, and are the normal form for large rivers on low-gradient country with a lot of sediment to move.
Etymology
A coinage, and an unusually well-documented one. Writing in the Journal of the Royal Geographical Society in 1834, Colonel J.R. Jackson proposed that channels which separate and reunite be called anastomosing branches, “or, if a word might be coined, anabranches” — contracting anastomosing and branch. Anastomosis is Greek for a cross-connection or opening, borrowed into English in 1615 out of anatomy.
Notes
The word never took hold in Britain and is now most at home in Australia, where the Great Anabranch of the Darling runs some 460 kilometers before returning to the parent river. An anabranch that gets cut off entirely becomes an oxbow lake — in Australia, a billabong.