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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 ?
Head black, except mandible, clypeus, gena, face near clypeus and shortly along orbits, ventral side of head around mouth ferruginous; antenna testaceous; mesosoma black, except lateral margins and posterior collar of pronotum testaceous; metasoma brown; legs testaceous, except distal extremities of tibiae darkened, part of metacoxa and outer side of club of metafemur brown.
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.
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.
Report on the testaceous Mollusca obtained during a dredging excursion in the Gulf of Suez in the months of February and March 1869.
Legs blackish brown, fore coxae partly luteous; fore trochanters, basal part of fore femora luteous; mid- and hind trochanters partly testaceous in males, mostly luteous in females, slightly darkened dorsally and posteriorly on distal part; fore tibia yellowish brown to luteous.
Urotergite IV-VI with 4 distinctive submedian and lateral spots on each segment, the submedian larger than the lateral; pygofer slightly testaceous in color.
Head black, except mandible testaceous; antenna brown; mesosoma black; metasoma brown; legs brown, except articulations and tarsal segments 1-4 testaceous.
Legs wholly black, mid femur with complete row of pv, upper calypter brownish suffused, lower calypter paler coei --Legs uniformly testaceous to dark brown, mid femur with 3-5 pv on basal half, calypters yellow to yellow-brown alaba 7.
Head black, except mandible partly testaceous; antenna brown-estaceous, except scape and pedicel testaceous; mesosoma black; metasoma brown; legs brown, except protibia and protarsus testaceous and first segment of meso- and metatarsus whitish.