What Does It Mean?: Apostle

ἀπόστολος  The Greek word apostolos (apostle) comes from the words “apo (away from)” and “stellein (to send),” meaning, “sent off.”  The idea is that of an “emissary” or “messenger,” sent with a message.  The designation of “apostle” was a function, not an office or position. Sometimes apostles were elected and at other times they were appointed. (Galatians 2:8; Romans 11:13; 1 Corinthians 4:17; 2 Corinthians 5:20, 8:18-23, 9:13; 1 Thessalonians 3:2.)

Remember that the early Christians operated from a Jewish understanding.  The Greek "apostle" is equivalent to the Hebrew “shaliah.” A shaliaḥ (שָלִיחַ‎; pl. שְלִיחִים, sheliḥim) was a Jewish legal emissary or agent who performed an act of legal significance for the sender(s).

The Twelve Apostles were called “emissaries” when they were “sent” (Matthew 10:1-8) They were usually called “the Twelve (τοῖς δώδεκα)” or “followers” (mathetai, μαθηταὶ). They were not leaders of individual churches, and others (Junia, Andronicus, Barnabas, Silas, Timothy, Apollos, and Paul himself) were called apostles.

In the biblical sense, it is entirely appropriate to refer to Padraig/Patrick (ca 387 - 493) as the Apostle to the Irish; John Eliot (ca 1604 -1690) as the Apostle to the Indians; and John G. Lake (1870-1935) as the Apostle to Africa.