deserter
noun /dɪˈzɜːtə(r)/
  /dɪˈzɜːrtər/
 - a person who leaves the army, navy, etc. without permission 
- He was convicted of hiding deserters.
 
Oxford Collocations DictionaryDeserter is used after these nouns:- army
 
Word Originmid 17th cent.: from desert ‘ abandon’, on the pattern of French déserteur.