D defs.my
Entry 1 sense Webster, 1913

Pneumatocyst

· Pneu·mat·o·cyst · IPA
01 n. A cyst or sac of a siphonophore, containing air, and serving as a float, as in Physalia.
  1. 1.
    A cyst or sac of a siphonophore, containing air, and serving as a float, as in Physalia.(Zool.)