Source : Webster's Revised Unabridged Dictionary (1913)

Hydrosome \Hy"dro*some\, Hydrosoma \Hy`dro*so"ma\, n. [NL.
   hydrosoma. See {Hydra}, and {-some} body.] (Zo["o]l.)
   All the zooids of a hydroid colony collectively, including
   the nutritive and reproductive zooids, and often other kinds.