Dentin

n. hard dense tissue which forms the main part of a tooth

Dentin (BE: dentine) is a calcified tissue of the body, and along with enamel, cementum, and pulp is one of the four major components of teeth. Usually, it is covered by enamel or cementum and lays over the pulp. By weight, seventy percent of dentin consists of the mineral, hydroxylapatite, twenty percent is organic material, and ten percent is water. Yellow in appearance, it greatly affects the color of a tooth due to the translucency of enamel. Dentin, which is less mineralized and less brittle than enamel, is necessary for the support of enamel.
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Dentin /den·tin/ the chief substance of the teeth, surrounding the tooth pulp and covered by enamel on the crown and by cementum on the roots. [more]Dentin - Community and Resources

Noun
1. a calcareous material harder and denser than bone that comprises the bulk of a tooth
(synonym) dentine
(hypernym) animal material
(hyponym) ivory, tusk
2. bone (calcified tissue) surrounding the pulp cavity of a tooth
(synonym) dentine
(hypernym) bone, os
(part-holonym) tooth

n. dentin, hard dense tissue which forms the main part of a tooth

adj. dentinal, of dentin