Definitions of desertion
the action of leaving a spouse, partner or dependant (=a person who relies on another for financial support, especially a family member) etc forever
After two unsuccessful studio recordings, there followed a period of alcoholism and desertion by his wife.
the crime of abandoning (=to leave forever) a person, cause, or organization in a way considered disloyal (=not supporting someone or something when you should)
The soldiers were prosecuted for desertion.