- to form into a union; esp., to organize (a group of workers in a shop, industry, etc.) into a labor union
- to bring into conformity with the rules, standards, etc. of a labor union
verbun·ion·ized, un·ion·iz·ing, un·ion·iz·es
- To organize into a labor union.
- To cause to join a labor union.
(third-person singular simple present unionizes, present participle unionizing, simple past and past participle unionized)