Strong's #646: apostasia (pronounced ap-os-tas-ee'-ah)

feminine of the same as 647; defection from truth (properly, the state) ("apostasy"):--falling away, forsake.

Thayer's Greek Lexicon:

̓́

apostasia

1) a falling away, defection, apostasy

Part of Speech: noun feminine

Relation: feminine of the same as G647

Citing in TDNT: 1:513, 88

Usage:

This word is used 2 times:

 

Acts 21:21: "are among the Gentiles to forsake Moses, saying that they ought not"
2 Thessalonians 2:3: "for that day shall not come, except there come a falling away first, and that man of sin"