All instruments of the harpsichord and spinet kind were styled virginals.
The virginal differed from the spinet in being square instead of triangular in form. The word pair was used in the obsolete sense of a set, as we read also of a pair of organs. The instrument is supposed to have obtained its name from young women, playing upon it.
This text comes from a footnote on a diary entry in the 1893 edition edited by Henry B. Wheatley.