"defection" in the noun sense
1. desertion, abandonment, defection
withdrawing support or help despite allegiance or responsibility
"his abandonment of his wife and children left them penniless"
2. apostasy, renunciation, defection
the state of having rejected your religious beliefs or your political party or a cause (often in favor of opposing beliefs or causes)
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License