The best replacement for caution is warning.

The best alternatives to caution are rated as following:
★★★★★  warning
★★★  conviction
★★★  danger
★★  precaution
★★  reprimand
★  warning osha
★  fixed penalty notice
  err on the side of caution
  arrest
  air on the side of caution
  courage
  error
  license freedom of speech

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

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



Google Trends

Scale is based on the average worldwide traffic of caution in all years. Click on graph for more.
caution
warning
conviction