protreptic
noun
pro·trep·tic prō-ˈtrep-tik 
: an utterance (such as a speech) designed to instruct and persuade
protreptic adjective
Word History
Etymology
Late Latin protrepticus hortatory, encouraging, from Greek protreptikos, from protrepein to turn forward, urge on, from pro- + trepein to turn
First Known Use
1678, in the meaning defined above