Definition of port-a-beul in US English:

port-a-beul

(also port-a-bheul, puirt-a-beul)

noun

Scottish
  • A fast-paced reel or dancing song consisting of a tune of Lowland Scottish origin to which repetitive, easily memorized Gaelic lyrics have been added, sung unaccompanied.

Origin

Early 20th century. From Scottish Gaelic port-a-beul from port + a, perhaps showing the preposition a from, out of (Early Irish a, as from the same Indo-European base as classical Latin ex) + beul mouth.