Two separate meanings here -
One is West Coast dances (see list)
http://brackenrigg.co.uk/dance_list.html
with the dances not being too formal, suitable for beginners, few dances having set tunes and at a bit more boisterous pace (a la Fergie MacDonald)


as opposed to Scottish Country Dancing on the East Coast with formal dances, experienced dancers, set tunes, set tempi (a la Shand)


Second meaning is a get-together for singing, poetry, recitation, music, anything else, with lots of dancing thrown in.