The Collaborative International Dictionary of English v.0.48:

Nonunion \Non*un"ion\, a.
   1. Not belonging to, or affiliated with, a trades union; as,
      a nonunion carpenter.
      [Webster 1913 Suppl.]

   2. Not employing trade union members; not recognizing or
      favoring trades unions or trades-unionists; as, a nonunion
      contractor; a nonunion subcontractor. -- Non*un"ion*ism,
      n.
      [Webster 1913 Suppl.]