'Folk song' definitions:

Definition of 'folk song'

noun

A song that is traditionally sung by the common people of a region and forms part of their culture [syn: folk song, folksong, folk ballad]

From: GCIDE

Folk \Folk\ (f[=o]k), Folks \Folks\ (f[=o]ks), n. collect. & pl. [AS. folc; akin to D. volk, OS. & OHG. folk, G. volk, Icel. f[=o]lk, Sw. & Dan. folk, Lith. pulkas crowd, and perh. to E. follow.]
1. (Eng. Hist.) In Anglo-Saxon times, the people of a group of townships or villages; a community; a tribe. [Obs.] [1913 Webster]
The organization of each folk, as such, sprang mainly from war. --J. R. Green. [1913 Webster]
2. People in general, or a separate class of people; -- generally used in the plural form, and often with a qualifying adjective; as, the old folks; poor folks. [Colloq.] [1913 Webster]
In winter's tedious nights, sit by the fire With good old folks, and let them tell thee tales. --Shak. [1913 Webster]
3. The persons of one's own family; as, our folks are all well. [Colloq. New Eng.] --Bartlett. [1913 Webster]
Folk song, one of a class of songs long popular with the common people.
Folk speech, the speech of the common people, as distinguished from that of the educated class. [1913 Webster]