inter- Look up inter- at Dictionary.com
L. inter (prep., adj.) "among, between," from PIE *enter "between, among" (cf. Skt. antar, O.Pers. antar "among, between," Gk. entera (pl.) "intestines," O.Ir. eter, O.Welsh ithr "among, between," Goth. undar, O.E. under "under"), a comparative of *en- "in." Also in certain L. phrases in Eng., such as inter alia "among other things." Spelled entre- in Fr., most words borrowed into Eng. in that form were re-spelled 16c. to conform with L. except entertain, enterprise.