Ethnomusicology
The study of social and cultural aspects of music and dance in local and global contexts. Specialists are trained primarily in anthropology and in music, but the multidisciplinary nature of the subject leads to different interpretations.
Folk Music
Music that has been submitted to the process of oral transmission. Acoustic music performed by a solo act or a small ensemble, often written by the performer(s), rendered in very simple arrangements, and dealing with social or personal issues to which most lay persons can easily relate.
World Music
This loosely defined term describes the local, folk, or roots music of a particular cultural group, society, or nation, oftentimes presented in conjunction with elements of religion, politics, and social customs. The term may refer to any music outside the western-art tradition.
The definitions above are derived from Oxford Music Online.