The gospels of to Matthew, Mark and Luke. “Synoptic” means “like-eyed” in Greek, so called by the Roman Church because these Gospels all see “eye to eye” with one another. Although these three texts contradict each other in a number of instances, all recount basically the same version of the story of Jesus. John, though part of the orthodox Christian canon, is radically different from Matthew, Mark and Luke, and is thus not “synoptic”.
The Church actively sought out and destroyed other, less “agreeable” gospels (see Gnosticism), including the Gospel of Thomas and the Gospel of Philip. It is even rumored there was a Gospel of Judas.