• (a.) Having the orbital index relatively small; having the orbits broad transversely; -- opposed to megaseme.
Mi'cro·seme adjective [ Micro- + Greek ... sign, mark: confer French microsème .] (Anat.) Having the orbital index relatively small; having the orbits broad transversely; -- opposed to megaseme . 
Type: Term Pronunciation: mī′krō-sēm Definitions: 1. Denoting a skull with an orbital index below 84.