From BiblePortal Wikipedia

Watson's Biblical & Theological Dictionary [1]

In the twelfth year of Christ, about the time that Archelaus was sent away from his government, a secession was made from the sect of the Pharisees, and a new sect arose, called the Galileans. Not long after this time, Judea, which was a Roman province, was added, for civil purposes, to Syria, over which Quirinus was governor. It happened, when the tax was levied by Quirinus, that one Judas, of Galilee, otherwise called Gaulonites, in company with Zaduk, a Sadducee, publicly taught, that such taxation was repugnant to the law of Moses, according to which the Jews, they maintained, had no king but God. The tumults which this man excited were suppressed,  Acts 5:37; but his disciples, who were called Galileans, continued to propagate this doctrine, and, farthermore, required of all proselytes that they should be circumcised. It was in reference to this sect that the captious question was proposed in  Matthew 22:17 , &c; namely, whether it was lawful to give tribute to Caesar. The Galileans, whom Pilate slew in the temple,  Luke 13:1-2 , appear to have been of this sect. By degrees, the Galileans swallowed up almost all the other sects; and it is highly probable that the zealots, particularly mentioned at the siege of Jerusalem, were of this faction.

Charles Buck Theological Dictionary [2]

A sect of the Jews which arose in Judea some years after the birth of our Saviour. They sprang from one Judas, a native of Gaulam, in upper Galilee, upon the occasion of Augustus appointing the people to be mustered, which they looked upon as an instance of servitude which all true Israelites ought to oppose. They pretended that god alone should be owned as master and lord, and in other respects were of the opinion of the Pharisees; but as they judged in unlawful to pray for infidel princes, they separated themselves from the rest of the Jews, and performed their sacrifices apart. As our Saviour and his apostles were of Galilee, they were suspected to be of the sect of the Galileans; and it was on this principle, as St. Jerome observes, that the Pharisees laid a snare for him, asking, Whether it were lawful to give tribute to Caesar? that in case he denied it, they might have an occasion of accusing him.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [3]

one of the names of reproach given to the early Christians. It was the ordinary phrase of Julian the apostate, when he spoke of Christ or Christians. He was accustomed to call Christ "the Galilaean God." Not only did be use this epithet himself, but made a law, requiring that no one should call the Christains by any other name, thinking thereby to abolish the name of Christians. He died fighting against them; and as he caught the blood in his hand which flowed from a wound in his side, he dashed it towards heaven, saying these memorable words: Vicisti, O Galilae! "Thou hast conquered, O Galilaean!" Bingham; Orig. Eccles. book 1, chapter 2, § 2.