(Gr. hairesis, usually rendered "heresy", Acts 24:14 ; 1 Chronicles 11:19 ; Galatians 5:20 , etc.), meaning properly "a choice," then "a chosen manner of life," and then "a religious party," as the "sect" of the Sadducees ( Acts 5:17 ), of the Pharisees ( 15:5 ), the Nazarenes, i.e., Christians ( 24:5 ). It afterwards came to be used in a bad sense, of those holding pernicious error, divergent forms of belief ( 2 Peter 2:1 ; Galatians 5:20 ).

These dictionary topics are from
M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition,
published by Thomas Nelson, 1897. Public Domain, copy freely.