Defn: An extensive order of Hydrozoa or Acalephæ. [Written also
Hydroida.]
Note: This order includes the hydras and the free-swimming hydromedusæ, together with a great variety of marine attached hydroids, many of which grow up into large, elegantly branched forms, consisting of a vast number of zooids (hydranths, gonophores, etc.), united by hollow stems. All the zooids of a colony are produced from one primary zooid, by successive buddings. The Siphonophora have also been included in this order by some writers. See Gymnoblastea, Hydromedusa, Gonosome, Gonotheca.
HYDROKINETIC
Hy`dro*ki*net"ic, a. Etym: [Hydro-, 1 + kinetic.]
Defn: Of or pertaining to the motions of fluids, or the forces which produce or affect such motions; — opposed to hydrostatic. Sir W. Thomson.
HYDROLOGICAL
Hy`dro*log"ic*al, a.
Defn: Of or pertaining to hydrology.
HYDROLOGIST
Hy*drol"o*gist, n.
Defn: One skilled in hydrology.
HYDROLOGY
Hy*drol"o*gy, n. Etym: [Hydro-, 1 + -logy: cf. F. hydrologie.]
Defn: The science of water, its properties, phenomena, and distribution over the earth's surface.