Boyd’s Bible Dictionary:

(way, school). A party adhering to a doctrine, as the sect of Sadducees (Acts 5:1717Then the high priest rose up, and all they that were with him, (which is the sect of the Sadducees,) and were filled with indignation, (Acts 5:17)), or Pharisees (Acts 15:5; 26:55But there rose up certain of the sect of the Pharisees which believed, saying, That it was needful to circumcise them, and to command them to keep the law of Moses. (Acts 15:5)
5Which knew me from the beginning, if they would testify, that after the most straitest sect of our religion I lived a Pharisee. (Acts 26:5)
). Christians in general were for a long time called by the Jews, in a spirit of contempt, “the sect of the Nazarenes” (Acts 24:55For we have found this man a pestilent fellow, and a mover of sedition among all the Jews throughout the world, and a ringleader of the sect of the Nazarenes: (Acts 24:5)). The word is also applied to a certain set of doctrines or mode of life (Acts 24:1414But this I confess unto thee, that after the way which they call heresy, so worship I the God of my fathers, believing all things which are written in the law and in the prophets: (Acts 24:14); 2 Peter 2:11But there were false prophets also among the people, even as there shall be false teachers among you, who privily shall bring in damnable heresies, even denying the Lord that bought them, and bring upon themselves swift destruction. (2 Peter 2:1)); and to heresies proper, or perversions of Christian truth (Gal. 5:2020Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, (Galatians 5:20)).

Concise Bible Dictionary: