time-waster

noun3

1. •
   Someone who wastes their own time or the time of others.

   • I showed him round the property thinking he was a prospective buyer, but in fact he was just a time-waster.
2. •
   Something which passes the time that may or may not be seen positively.

   • This puzzle book is a good time-waster when my train is late.
3. •
   (informal) Something unproductive.

   • Email was supposed to improve business efficiency, but all too often it turns out to be a time-waster.