exordium - /ɪɡˈzɔːdɪəm,ɛɡˈzɔːdɪəm/

noun: exordium; plural noun: exordia; plural noun: exordiums

the beginning or introductory part, especially of a discourse or treatise.

Late 16th century: from Latin, from exordiri 'begin', from ex- 'out, from' + ordiri 'begin'.