Definition
To work slowly by strictly following all work rules, usually in a work-to-rule job action, as part of unionized labor protest.
How People Actually Use It
A type of labor action, somewhere between normal working conditions and a strike, where workers will do only what the collective bargaining agreement requires them to do, and nothing more, such as refusing to work overtime. It is a pressure tactic, designed to get an employer back to the bargaining table to hammer out a new contract acceptable to the employees. Also known as quiet quitting.
"When teachers were not getting what they were asking for during contract talks, they went on work-to-rule, suspending extracurricular activities and after class student meetings."
Source: Urban Dictionary