‖n.; pl. Episterna [ NL. See Epi-, and Sternum. ] 1. (Anat.) (a) A median bone connected with the sternum, in many vertebrates; the interclavicle. (b) Same as Epiplastron. [ 1913 Webster ]

2. (Zoöl.) One of the lateral pieces next to the sternum in the thorax of insects. [ 1913 Webster ]