A Dictionary of Music and Musicians/Semifusa
SEMIFUSA. The Latin name for the Semiquaver; but sometimes applied to the Quaver also. The etymology of the term is not very clear. The most probable theory is that which traces it to a fancied resemblance between the early form of the Quaver, and that of a spindle (fusus). [See Semicroma, Semiquaver, Semiminima, Quaver, Notation.]
[ W. S. R. ]