un·ion·ist 
(ynyə-nĭst)
(ynyə-nĭst)n.
1.
a. One who believes in or supports labor unions.
b. A member of a labor union.
2. Unionist
a. One who is loyal to the United Kingdom, especially in support of its sovereignty over Northern Ireland.
b. One who was loyal to the federal government of the United States during the Civil War.
un′ion·istic adj.