undocumented

Short definition from Wiktionary

Adjective

1. 1
   Lacking instructions or reference material.
2. 2
   Not having official documents that provide identification, authorization, etc.
3. 3
   Not having official documents that provide identification, authorization, etc: Not having official documentation required to legally enter, reside in, or work in a country.

Noun

1. 1
   Synonym of undocumented immigrant.