The Collaborative International Dictionary of English v.0.48:
Hemi-demi-semiquaver \Hem`i-dem`i-sem"i*quaver\, n. [Hemi- + demi-semiquaver.] (Mus.) A short note, equal to one fourth of a semiquaver, or the sixty-fourth part of a whole note. [1913 Webster]WordNet (r) 3.0 (2006):
hemidemisemiquaver n 1: a musical note having the time value of a sixty-fourth of a whole note [syn: sixty-fourth note, hemidemisemiquaver]