zero-hours
adjective /ˈzɪərəʊ aʊəz/
  /ˈzɪrəʊ aʊərz/
(also zero-hour)
 [only before noun] (British English)- used to describe or refer to a contract of employment in which the employee is not guaranteed regular hours of work and is only paid for the hours they actually work- Workers on zero-hours contracts do not know how much they will earn from week to week.
- The company is taking on more zero-hours workers.