usually defined as someone or a party that consciously abandons their home or default party, country or military affiliation and is usually considered illegal by the default association.
the definition started in the military, as someone who "defects" to the opposing party...meaning "to switch sides".
commonly used for refugees attempting to leave north korea. see example below:
"north korea is a nightmare. i know someone who actually managed to defect from that communist hellhole and apply for legal status in south korea as a defector"