Definition of "massa"

"All well, Massa Challenger, all well!" he cried. "Me stay here. No fear. You always find me when you want." His honest black face, and the immense view before us, which carried us half-way back to the affluent of the Amazon, helped us to remember that we really were upon this earth in the twentieth century, and had not by some magic been conveyed to some raw planet in its earliest and wildest state.

1912, Arthur Conan Doyle, The Lost World […], London, New York, N.Y.: Hodder and Stoughton