O.E. apostol "messenger," esp. the 12 witnesses sent forth by Jesus to preach his Gospel, from L.L. apostolus, from Gk. apostolos "messenger, person sent forth," from apostellein "send away, send forth," from apo- "away" (see apo-) + stellein "to send" (cf. epistle). The current form of the word, predominant since 16c., is infl. by O.Fr. apostle (12c.), from the same L.L. source. Fig. sense of "chief advocate of a new principle or system" is from 1810. Apostles, short for "The Acts and Epistles of the Apostles," is attested from c.1400. Apostolic is late 15c., from L. apostolicus, from Gk. apostolikos.