The best replacement for drone is uav.

The best alternatives to drone are rated as following:
★★★★★  uav
★★★  worker bee
★★★  rc
★★  remote control
★★  shotgun
★★  drone
★★  worker
★★  explosive drone
★★  travis
★  rpa
★  ufo
★  fighter jet
★  quadcopter
★  smart start
★  helicopter
★  rc helicopter
★  probe
★  qrx 350 drone
  dji phantom
  ar drone 2
  viper smartstart
  scv
  phantom
  defense drone mass effect 3
  predator drone
  defense drone

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

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



Google Trends

Scale is based on the average worldwide traffic of drone in all years. Click on graph for more.
drone
uav
worker bee