Webster’s Revised Unabridged Dictionary · 1913 Hydrosome Hy′dro·some (·sōm), Hy′dro·so′ma (·sō′mȧ), n. [NL. hydrosoma. See Hydra, and -some body.] (Zoöl.) All the zooids of a hydroid colony collectively, including the nutritive and reproductive zooids, and often other kinds. ‹ Hydroscope Hydrosorbic ›