WordWeb Online

1. Recruit for a union or organize into a union
   "We don't allow people to come into our plant and try to unionize the workers"
   - unionise [Brit]
    
2. Form or join a union
   "The auto workers decided to unionize"
   - unionise [Brit], organize, organise [Brit]

Derived forms: unionizing, unionizes, unionized

See also: union, unionization

Type of: enrol [Brit, Cdn], enroll [N. Amer], enter, fall in, get together, inscribe, join, recruit