(Hy*drog"e*nous) a. Of or pertaining to hydrogen; containing hydrogen.
(Hy*drog"no*sy) n. [Hydro-, 1 + Gr. knowledge.] A treatise upon, or a history and description
of, the water of the earth.
(Hy"drog*ode) n. [Hydrogen + Gr. way. path.] (Elec.) The negative pole or cathode. [R.]
(Hy*drog"ra*pher) n. One skilled in the hydrography; one who surveys, or draws maps or
charts of, the sea, lakes, or other waters, with the adjacent shores; one who describes the sea or other
(Hy`dro*graph"ic Hy`dro*graph"ic*al) a. Of or relating to hydrography.
(Hy*drog"ra*phy) n. [Hydro-, 1 + -graphy: cf. F. hydrographie.]
1. The art of measuring and describing the sea, lakes, rivers, and other waters, with their phenomena.
2. That branch of surveying which embraces the determination of the contour of the bottom of a harbor
or other sheet of water, the depth of soundings, the position of channels and shoals, with the construction
of charts exhibiting these particulars.
(Hy*drog"u*ret) n. [From Hydrogen.] (Chem.) A hydride. [Obs.]
(Hy"droid) a. [Hydra + - oid.] (Zoöl.) Related to, or resembling, the hydra; of or pertaining to the
Hydroidea. n. One of the Hydroideas.
(||Hy*droi"de*a), n. pl. [NL. See Hydra, and -oid.] (Zoöl.) An extensive order of Hydrozoa or
Acalephæ. [Written also Hydroida.]
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 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.