Easton's Bible Dictionary: M. G. Easton, M.A., D.D.
To draw back or apostatize in matters of religion (Acts 21:21; 2 Th. 2:3; 1 Tim. 4:1). This may be either partial (Pr. 14:14) or complete (Heb. 6:4-6, 10:38, 39). The apostasy may be both doctrinal and moral.