1) Latin phrase 
Docere is a Latin word that means to instruct, teach, or point out. Cicero first introduced this term in his book De Oratore. Cicero wrote this book in 55 BC as a dialogue to describe the ideal speaker and imagine him as a moral guidance of the state. He suggested that there are three duties or goals of rhetoric. He described these as `to teach, ....
To teach; viewed by Cicero as one of the three goals of rhetoric.