Webster's Revised Unabridged Dictionary · 1913

Episternum

Episternum , noun

[New Latin See Epi-, and Sternum.]

1.
(a) (Anatomy) A median bone connected with the sternum, in many vertebrates; the interclavicle.
(b)
(Anatomy) Same as Epiplastron.
2.
(Zoology) One of the lateral pieces next to the sternum in the thorax of insects.