“Hiddekel” means rapid

Hiddekel: one of the rivers of Eden, the river which "goeth eastward to Assyria," (Genesis 2:14) and which Daniel calls "the great river," (Daniel 10:4) seems to have been rightly identified by the LXX. with the Tigris. Dekel is clearly an equivalent of Digla or Dighath, a name borne by the Tigris in all ages. The name now in use among the inhabitants of Mesopotamia is Dijleh .