Couple of days ago a friend of mine asked me what is the term for making and flying Rc planes,I said it is Aeromodelling.
then he asked me then what is the term for Rc boats and cars? and was it also Aeromodelling
I was confused and told him that I will check it out and tell him

Ok so the question stand for everyone here-

"Are R/C Cars and Boats also included in the term 'Aeromodelling'?

no
'aero' (To do with air) modelling. it is in the name. it is the broader category of RC , which includes anything that is Radio Controlled. What is RC Boating and RC Bashing () called , not a clue

well, i guess it is not the correct term for building RC cars and boat because
Areomodelling is a term something related to air and where as cars and boats are the vehicles not related to mid air

BUT STILL IT IS LITTLE CONFUSING  

Than what is the term used for building cars and boats??

For cars,I would say there are the 2 basic categories.

Competitive RC car racing(guys doing this are called as 'racers' or 'rc car racers' or 'model car racers.')

and

casual driving(referred to as "bashing" among car guys).(Guys who do this are typically known as "bashers")

Once you go into the intricacies of racing,you see classes first.Usually 1/12(typically on-road stuff),1/10(on-road and off-road),1/8(on road and off road) and 1/5(on road and off road).Then,you have dirt oval racing and rock crawling and drifting.These are the basic classes.

Hope this answers a part of your question.