Literally, "away from standing", that is, departure. Used 2 times in the NT, Acts 21, I think, some accusing Paul of "teaching departure from Moses", and, 2 Thessalonians 2, "that day will not come but the apostasia come first, and the man of sin be revealed".I heard a sermon once that used the analogy of a person standing in a shower of grace. As long as they stand in the place where grace showers upon them they are in the position of holiness, but if they walk away from that position [apostasise] they become estranged from grace and the holiness it provides.
Apostasy by definition means moving away from a position.
[Middle English apostasie, from Old French, from Late Latin apostasia, defection, from Late Greek apostasiā, from Greek apostasis, revolt, from aphistanai,
apo-
or
ap-
prefix
1. away from; off: apogee.
2. indicating separation of: apocarpous.
3. indicating a lack or absence of: apogamy.
4. indicating derivation from or relationship to: apomorphine.
[from Greek apo away, off]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
histanai, to stand, place; see stā- in Indo-European roots.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
It's used a number of times in the LXX, all, if I remember correctly, that have a certain context, that context is rebellion or along that line.
Much love!