1. To detain or restrain someone, either physically or figuratively. Likened to grabbing someone by the collar. I was trying to get out of the office early, but my boss collared me on my way out. I spent all afternoon running around collaring the kids to bring them in for supper. I thought I'd be able to sneak out of the assembly, but one of the nuns collared me and pulled me back inside.
2. Of police, to arrest or detain someone, such as a suspect of a crime. Police were able to collar the suspect after he fled down one of the neighborhood's back alleys.
See also: collar