The Collaborative International Dictionary of English v.0.48:

evangelist \e*van"gel*ist\ ([-e]*v[a^]n"j[e^]l*[i^]st), n. [F.
   ['e]vang['e]liste, L. evangelista, fr. Gr. e'yaggelisth`s.]
   A bringer of the glad tidings of Church and his doctrines.
   Specifically:
   (a) A missionary preacher sent forth to prepare the way for a
       resident pastor; an itinerant missionary preacher.
   (b) A writer of one of the four Gospels (With the definite
       article); as, the four evangelists, Matthew, Mark, Luke,
       and John.
   (c) A traveling preacher whose efforts are chiefly directed
       to arouse to immediate repentance.
       [1913 Webster]

             The Apostles, so far as they evangelized, might
             claim the title though there were many evangelists
             who were not Apostles.               --Plumptre.
       [1913 Webster]

WordNet (r) 3.0 (2006):

evangelist
    n 1: a preacher of the Christian gospel [syn: evangelist,
         revivalist, gospeler, gospeller]
    2: (when capitalized) any of the spiritual leaders who are
       assumed to be authors of the Gospels in the New Testament:
       Matthew, Mark, Luke, and John

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "evangelist":
   Ambrose of Milan, Athanasius, Barnabas, Basil,
   Clement of Alexandria, Clement of Rome, Cyprian of Carthage,
   Cyril of Jerusalem, Gabriel, Gregory of Nyssa, Hermas, Ignatius,
   Irenaeus, Jerome, John, John Chrysostom, Justin Martyr,
   Lactantius Firmianus, Luke, Mark, Origen, Papias, Paul, Peter,
   Polycarp, Tertullian, adorer, ante-Nicene Fathers, apostle,
   beadsman, celebrant, chapelgoer, churchgoer, colporteur,
   communicant, congregation, converter, daily communicant, disciple,
   evangel, forerunner, harbinger, herald, herald angel, idolater,
   missionary, missionary apostolic, missionary rector, missioner,
   petitioner, prayer, propagandist, proselyter, proselytizer,
   revivalist, saint, suppliant, supplicant, supplicator, venerator,
   votary, worshiper



Easton's 1897 Bible Dictionary:

Evangelist
   a "publisher of glad tidings;" a missionary preacher of the
   gospel (Eph. 4:11). This title is applied to Philip (Acts 21:8),
   who appears to have gone from city to city preaching the word
   (8:4, 40). Judging from the case of Philip, evangelists had
   neither the authority of an apostle, nor the gift of prophecy,
   nor the responsibility of pastoral supervision over a portion of
   the flock. They were itinerant preachers, having it as their
   special function to carry the gospel to places where it was
   previously unknown. The writers of the four Gospels are known as
   the Evangelists.


The Devil's Dictionary (1881-1906):

EVANGELIST, n.  A bearer of good tidings, particularly (in a religious
sense) such as assure us of our own salvation and the damnation of
our neighbors.