'Bougwan' is a term meaning master in African. In general terms it is used when a dieing woman of inferior caste is in a cave (mortally wounded by an old witch doctor) and wishes to confess her undieing love for a adventurous English gentleman.
The word has fallen out of fashion since the decline of Empire, and indeed it is difficult to see under what circumstances it would today be used.
"Ah! Bougwan, I die!" gasped the beautiful creature. "She crept out-- Gagool; I did not see her, I was faint--and the door began to fall; then she came back, and was looking up the path--I saw her come in through the slowly falling door, and caught her and held her, and she stabbed me, and I die, Bougwan!"
"Say to my lord, Bougwan, that--I love him, and that I am glad to die because I know that he cannot cumber his life with such as I am, for the sun may not mate with the darkness, nor the white with the black."