Source : Webster's Revised Unabridged Dictionary (1913)

Unionism \Un"ion*ism\, n.
   1. The sentiment of attachment to a federal union, especially
      to the federal union of the United States.

   2. The principles, or the system, of combination among
      workmen engaged in the same occupation or trade.

Source : WordNet®

unionism
     n : the system or principles and theory of labor unions [syn: {trade
         unionism}]