prosimian Syllabification: (pro·sim·i·an)Pronunciation: /prōˈsimēən/ ZoologyDefinition of prosimian noun a primitive primate of a group that includes the lemurs, lorises, bushbabies, and tarsiers. Suborder Prosimii, order Primates: several families adjective of or relating to the prosimians. Compare with simian.Origin: late 19th century: from pro-2 'before' + simianprosimian in other Oxford dictionaries Definition of prosimian in the British & World English dictionary