be working overtime- To be working more hours at one's job than one is scheduled or required to do. I've been working overtime all week to get this project done by the deadline.
To be putting forth a lot of effort to do or accomplish something-Everyone's air conditioners have been working overtime during this heat wave.
Mom has been working overtime to get more signatures on her petition for the city council.
Chinese overtime- Overtime pay which is calculated at less than an employee's normal hourly rate (usually one-half), rather than one-and-a-half times it, as is usually paid in traditional overtime arrangements. It is a potentially derogatory term, so discretion is advised.
Overall, I love having the flexibility to work the hours that I see fit; the only downside is that I only get Chinese overtime when I have to put in more time for a project than usual.
If someone or something is working overtime, they are working very hard in order to achieve something. The team had been working overtime to improve the party's image.