. Why isn't the more recent "aerostat" a better description than "tethered aerostat"? The latter phrase seems tautologous.
Bigbux. I think it's a reasonable question.
"Aerostat" is by no means a recent term, only its incorrect adoption.
You have to look at the family of aircraft, which, by convention, is broadly divided into two main classes: " aerodynes" and "aerostats".
Aerodynes are heavier-than-air craft that need to maintain themselves airborne in the atmosphere by self-generated aerodynamic force (i.e. sourced from a power plant). This category includes aeroplanes ( fixed wing) and rotorplanes (including helicopters and gyroplanes) .
In contrast, aerostats are lighter-than-air craft which are normally buoyant in the atmosphere. These can also be broadly divided into two classes. Those that lack a propulsion system ( "balloons") and those that are capable of being guided or steered," dirigibles" or airships. All these "blimps", "Zeppelins"
et al are still also correctly defined as aerostats.
The "stat" part of aerostat therefore does not refer to it being static over the ground because it is on a tether. The confusion arises when other forms of aerostat need to be compared or contrasted. For example, free-flying balloons have been used in fairly recent times for reconnaissance and even long range bombing. Dirigible aerostats are still being built or proposed for a number of purposes, from surveillance to air transport.
Thus I do not consider it being pedantic to continue to try to use these definitions correctly.