The spelling of the word "kafirboom" can be explained using the International Phonetic Alphabet (IPA). It is pronounced as [kɑːfɪərbum], where the stress is on the first syllable. The first part of the word, "kafir," refers to a non-believer in Islam. The second part, "boom," is a South African word for "tree." Therefore, the "kafirboom" refers to a tree that is considered to be an infidel by Muslims. This term is usually used in a derogatory sense and is not commonly used in modern language.