Source : Webster's Revised Unabridged Dictionary (1913)

Vibraculum \Vi*brac"u*lum\, n.; pl. {Vibracula}. [NL., dim. from
   L. vibrare to vibrate.] (Zo["o]l.)
   One of the movable, slender, spinelike organs or parts with
   which certain bryozoans are furnished. They are regarded as
   specially modified zooids, of nearly the same nature as
   Avicularia.