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 unionise the workers"
   - unionize
    
2. Form or join a union
   - unionize, organize, organise [Brit]

Derived forms: unionises, unionising, unionised

See also: unionisation [Brit]

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