The best replacement for responsive is mobile.

The best alternatives to responsive are rated as following:
★★★★★  mobile
★★★★★  adaptive
★★★★  reactive
★★★★  fluid
★★★★  unresponsive
★★★  responsible
★★★  native
★★  cushioned
★★  bootstrap
★  adaptive website
★  efficient supply chain
★  app
★  fixed layout
★  native app
★  separate mobile site
★  mobile first
  m dot
  efficient
  assertive
  mobile website
  fully benefit responsive
  cushioned sockliner
  efficient supply chains

Your alternative for responsive is not listed? Suggest!
Speaking about responsive, one probably shouldn't forget about bootstrap.

Other search terms related to responsive and their ratings are:
★★★★★ bootstrap
★★ bootstrap 3
You have in mind a companion for responsive and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of responsive in all years. Click on graph for more.
responsive
mobile
adaptive