From the Horizon 2020 - Work Programme 2016-17: General Annex:

Where a topic description refers to a TRL, the following definitions apply, unless otherwise specified:

  • TRL 1 – basic principles observed
  • TRL 2 – technology concept formulated
  • TRL 3 – experimental proof of concept
  • TRL 4 – technology validated in lab
  • TRL 5 – technology validated in relevant environment (industrially relevant environment in the case of key enabling technologies)
  • TRL 6 – technology demonstrated in relevant environment (industrially relevant environment in the case of key enabling technologies)
  • TRL 7 – system prototype demonstration in operational environment
  • TRL 8 – system complete and qualified
  • TRL 9 – actual system proven in operational environment (competitive manufacturing in the case of key enabling technologies; or in space)

Found from an answer about pointless academic research on StackExchange network. I agree with the answer that academic research should bring an idea from TRL 1 to TRL 4-6. Then startups should take the idea from TRL 4-5 to TRL 7-8. Competition should pop up at about TRL 9.