hydroidadj.n.
/ˈhʌɪdrɔɪd/, U.S. /ˈhaɪˌdrɔɪd/ A. adj. Zoology. Resembling or allied to the genus hydra n. of Hydrozoa.
a. Belonging to the order or subclass Hydroidea, of which Hydra is the typical genus.
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the world > animals > invertebrates > subkingdom Metazoa > grade Diploblastica > phylum Coelenterata > [adjective] > of class Hydrozoa > belonging to order Hydroidea
hydroid1864
1864 in Webster's Amer. Dict. Eng. Lang.
1867 J. Hogg Microscope (ed. 6) i. iii. 227 Hydroid zoophytes with expanded tentacles.
1888 G. Rolleston & W. H. Jackson Forms Animal Life (ed. 2) 746 Colonies containing polymorphic hydroid individuals, and generally medusoid as well.
b. Of the nature of a hydroid (see sense B. 1(b)): opposed to medusoid.
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the world > animals > invertebrates > subkingdom Metazoa > grade Diploblastica > phylum Coelenterata > [adjective] > of class Hydrozoa > belonging to order Hydroidea > of nature of a hydroid
hydroid1877
1877 T. H. Huxley Man. Anat. Invertebrated Animals iii. 132 Some medusoids..the hydroid stages of which are not..known.
B. n.
1. Zoology (a) A Hydrozoan belonging to the Hydroidea. (b) One of the two forms of zooids occurring in Hydrozoa, resembling Hydra in structure, but typically asexual: opposed to Medusa.
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the world > animals > invertebrates > subkingdom Metazoa > grade Diploblastica > phylum Coelenterata > [noun] > class Hydrozoa > member of order Hydroidea
hydroid1865
hydranth1874
hydroidean1888
the world > animals > invertebrates > subkingdom Metazoa > grade Diploblastica > phylum Coelenterata > [noun] > class Hydrozoa > member of > zooid
hydroid1865
1865 E. C. Agassiz & A. Agassiz Seaside Stud. Nat. Hist. 21 Below these [Ctenophorae and Discophorae] come the Hydroids, embracing the most minute..of all these animals.
1880 Libr. Universal Knowl. I. 332 The fixed hydroids and swimming jelly-fishes are alternate forms assumed by the successive generations of the same animal.
1888 G. Rolleston & W. H. Jackson Forms Animal Life (ed. 2) 745 The Hydroid is (1) a permanent locomotor sexual form, multiplying by gemmation, but only temporarily colonial,—Hydra: (2) a larval form which passes by a metamorphosis into a Medusa: (3) a non-sexual but permanent form, sometimes solitary, usually however multiplying by gemmation..giving origin to colonies: (4) a locomotor sexual form..never multiplying by gemmation.
2. Botany. [ < German hydroid (H. Potonié 1883, in Jahrb. K. Bot. Gartens Berlin II. 243).] An element forming part of the hydrome n. tissue of a plant.
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the world > plants > part of plant > cell or aggregate tissue > [noun] > tissue > water-conducting section
hydroid1887
hydrome1900
1887 W. Hillhouse tr. E. Strasburger Handbk. Pract. Bot. v. 58 The perfect wood-cells..consist only of dead cell-walls, and, as..they simulate the tracheæ, i.e. vessels, they are known as tracheïdes, more recently as hydroïdes.
1902 A. G. Tansley in Encycl. Brit. XXV. 409/2 Such differentiated water-conducting cells we call hydroids, the tissue they form hydrom.
1929 Encycl. Brit. XVIII. 6/1 Dead water-conducting cells (hydroids).
1968 P. R. Bell & C. L. F. Woodcock Diversity Green Plants iv. 126 Surrounding a core of tracheid-like cells (sclereids), containing scattered thin-walled cells (hydroids), is a zone of cells conspicuously large in transverse section.
1971 E. V. Watson Struct. & Life Bryophytes (ed. 3) ix. 126 Collectively these tissues are known as hadrom and leptom (analogues respectively of xylem and phloem) but the constituent elements are conveniently termed hydroids and leptoids.
This entry has not yet been fully updated (first published 1899; most recently modified version published online March 2022).
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adj.n.1864