(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).

Noah Webster's New International Dictionary of the English Language

1. (n.) A cutting; a scion.

2. (n.) Those following a particular leader or authority, or attached to a certain opinion; a company or set having a common belief or allegiance distinct from others; in religion, the believers in a particular creed, or upholders of a particular practice; especially, in modern times, a party dissenting from an established church; a denomination; in philosophy, the disciples of a particular master; a school; in society and the state, an order, rank, class, or party.