The name Haddakel in the Bible
The Haddakel, a.k.a Hiddakel or Hiddekel, is the third of four rivers of Eden (the others being Pishon, Gihon, and Parat). Although most translations mention this river by its modern name Tigris, in the Bible this river is consistently called Haddakel. According to Genesis 2:14, this river flows east of Assyria.
Etymology of the name Haddakel
Fuerst's Hebrew & Chaldee Lexicon to the Old Testament suggests that this name is derived from the verb חדק (hdq), meaning to prick:
But this does not explain the letter lamed in the name Haddakel. The word דקל (daqel) denotes a date tree palm. In this sense the name Haddakel would be related to the name Diklah.
More interesting and more common, however, are the words חד (had), meaning sharp:
And either of the words קל (qal/qol) meaning swift or frivolity:
For a meaning of the name Haddakel, NOBSE Study Bible Name List reads Rapid, but more complete would be Sharp Rapids. Jones' Dictionary of Old Testament Proper Names renders The Rapid Swift.