John O' Brien's Foclóir Gaoidhilge Sax-Bhéarla of 1768, p510, has the following entry: U'RSHNAIDHM, or ûrshnaidhm, a knot or tie; also the pin or Jack, that fastens the wires on a harp. http://books.google.fr/books?vid=OCLC03435727&id=C30CAAAAQAAJ&printsec=titlepage#PRA2-PA510,M1