large lizard of the American tropics, 1550s, from Spanish, from Arawakan (West Indies) iguana, iwana, the local name for the lizard.

Foure footed beastes ... named Iuannas, muche lyke vnto Crocodiles, of eyght foote length, of moste pleasaunte taste. [Richard Eden, "Decades of the New World," 1555]