1.NounA large venomous snake found in Africa, taxonomic name Dendroaspis polylepis. Despite the name, this species of snake is not black; its colour ranges widely from olive-brown, khaki or grey, sometimes to darker hues, especially when old. The inside of the mouth is black, but in spite of a recent urban legend there is no indication that that has anything to do with the name "black mamba", which is a much older usage than any such suggestion.