Macumba is a word of African (Bantu) origins. Various explanations of its meaning include "a musical instrument", the name of a Central African deity, and simply "magic". It was the name used for all Bantu religious practices mainly in Bahia Afro-Brazilian in the 19th century. In the 20th century, these practices re-aligned themselves into what are now called Umbanda, Quimbanda and Omoloko. The term "macumba" became common in some parts of Brazil and it is used by most people as a pejorative meaning "black witchcraft".
The word "macumba" is frequently used in Brazil to refer to any ritual or religion of African origin (as slang), and although its use by non-practitioners remains largely pejorative in intent (referring to all sorts of religious (or otherwise) superstitions and luck-related rituals and beliefs), and is considered offensive, its use among actual practitioners is not viewed negatively. In Brazil one can find expressions such as "chuta que é macumba!" ("kick it, it is witchcraft!") to show disagreement with bad luck.
Read more about Macumba: In Brazil