The Collaborative International Dictionary of English v.0.48:
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.
1. (Eng. Hist.) In Anglo-Saxon times, the people of a group
of townships or villages; a community; a tribe. [Obs.]
The organization of each folk, as such, sprang
mainly from war. --J. R. Green.
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.
In winter's tedious nights, sit by the fire
With good old folks, and let them tell thee tales.
3. The persons of one's own family; as, our folks are all
well. [Colloq. New Eng.] --Bartlett.
Folk song, one of a class of songs long popular with the
Folk speech, the speech of the common people, as
distinguished from that of the educated class.