Source : Webster's Revised Unabridged Dictionary (1913)

Glochidium \Glo*chid"i*um\, n.; pl. {Glochidia}. [NL., fr. Gr. ?
   the point of an arrow.] (Zo["o]l.)
   The larva or young of the mussel, formerly thought to be a
   parasite upon the parent's gills.

Source : WordNet®

glochidium
     n : a barbed spine or bristle (often tufted on cacti) [syn: {glochid}]
     [also: {glochidia} (pl), {glochidcia} (pl)]

glochidia
     See {glochidium}