Entomology an internal process or system of processes of the sternum of an arthropod. [ < scientific Latin entosternum (1821 or earlier) < ento-ento- + sternumsternumn.]
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1902 Encycl. Brit. XXV. 527/2 The affinity between Limulus and the Arachnids, indicated by the presence of a free suspended entosternum or plastron or entosternite in both.