deserter

noun

1. a disloyal person who betrays or deserts his cause or religion or political party or friend etc.

   noun.person

   Synonyms apostate ratter recreant renegade turncoat

   Source: WordNet 3.0

2. a person who abandons their duty (as on a military post)

   noun.person

   Synonyms defector

   Source: WordNet 3.0

3. One who forsakes a duty, a cause or a party, a friend, or any one to whom he owes service; especially, a soldier or a seaman who abandons the service without leave; one guilty of desertion.

   noun

   Source: webster1913