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1. Biology
a. Having a hard shell or shell-like outer covering: testaceous echinoderms.
b. Composed of a shell or shell-like material: a testaceous operculum.
2. Having the reddish-brown or brownish-yellow hue of bricks.

[From Latin testāceus, from testa, shell.]


1. (Biology) of, relating to, or possessing a test or testa
2. (Biology) of the reddish-brown colour of terra cotta
[C17: from Latin testācens, from testa]


(tɛˈsteɪ ʃəs)

1. of, pertaining to, or derived from shells.
2. having a test or shell-like covering.
3. of a brick-red, brownish red, or brownish yellow color.
[1640–50; < Latin testāceus shell-covered =test(a) (see test2) + -āceus -aceous]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Adj.1.testaceous - relating to or possessing a testa or hard shell; "testaceous fish"
References in periodicals archive ?
The Mineral Conchology of Great Britain; or Coloured Figures and Descriptions of Those Remains of Testaceous Animals or Shells Which Have Been Preserved at Various Times and Depths in the Earth, 1, 1-19.
Report on the marine testaceous Mollusca of the north-east Atlantic and neighbouring seas.
Big and large; all body covered with yellow or ash colored on the testaceous or reddish ground, with black prothorax and head.
Thorax: Mesonotum red chestnut, with white tomentum and defined longitudinal testaceous bands; pleura and humeral callus orange with fine white tomentum; anterior and posterior spiracles pale yellow; legs with coxae, trochantes and femora orange, mid and posterior femora with apexes dark chestnut; mid femur with three apical posterodorsal setae and one antero-medial setae.
COLORATION: Dorsum coloration variable, from reddish brown with pale markings to pale brown with reddish markings; head either testaceous or reddish brown, with median longitudinal sulcus darker; AI orange, red or yellow, AII, AIII, and AIV usually yellow, with bases and apices redor orange.
But our deluded people attributed the victory not only to their fetishes, but also to every cartilaginous, spinous, and testaceous creature in the sea, which they consider, to the present day, as warriors of their fetish Nai (the sea).
Coleoptera Leptinidae Leptinus testaceous Coleoptera Leptodiridae Namadus sp.
Sowerby's second most important publication, Mineral Conchology of Great Britain, or Coloured Figures and Descriptions of those Remains of Testaceous Animals, or Shells which have been Preserved at Various Times, and Depths in the Earth (London 1812-1846), is actually a work of invertebrate paleontology (a term that had not yet come into use in Sowerby's day) and it recorded, for the first time, many index fossils found in England.
Body testaceous-ferruginous, except petiole black; antenna brown, except segments 1 and 2 testaceous and segment 10 whitish.
Report on the testaceous Mollusca obtained during a dredging excursion in the Gulf of Suez in the months of February and March 1869.