| Noun | 1. | Siphonophora - marine colonial hydrozoans animal order - the order of animals class Hydrozoa, Hydrozoa - coelenterates typically having alternation of generations; hydroid phase is usually colonial giving rise to the medusoid phase by budding: hydras and jellyfishes siphonophore - a floating or swimming oceanic colony of polyps often transparent or showily colored genus Nanomia - a genus of Siphonophora genus Physalia, Physalia - Portuguese man-of-war |