The Collaborative International Dictionary of English v.0.48:

Semiquaver \Sem"i*qua`ver\ (s[e^]m"[i^]*kw[=a]`v[~e]r), n.
   (Mus.)
   A note of half the duration of the quaver; -- now usually
   called a sixteenth note.
   [1913 Webster]

WordNet (r) 3.0 (2006):

semiquaver
    n 1: a musical note having the time value of a sixteenth of a
         whole note [syn: sixteenth note, semiquaver]