No, we should not add drone as a tag synonym for uav.
After some thought and discussion in answers here on the taxonomy needed, I have suggested tag wiki entries for uav, auv and ugv.
If someone asks a question not covered by these tags and has to use the suggested drone tag instead, then I'll create a tag wiki for that too, following the same format.
Unmanned ground vehicle.
From the Wikipedia page:
An unmanned ground vehicle (UGV) is a vehicle that operates while in contact with the ground and without an onboard human presence. UGVs can be used for many applications where it may be inconvenient, dangerous, or impossible to have a human operator present. Generally, the vehicle will have a set of sensors to observe the environment, and will either autonomously make decisions about its behavior or pass the information to a human operator at a different location who will control the vehicle through teleoperation.
The UGV is the land-based counterpart to unmanned aerial vehicles and remotely operated underwater vehicles. Unmanned robotics are being actively developed for both civilian and military use to perform a variety of dull, dirty, and dangerous activities.