what is armature winding?
The winding from which you will get the output will be termed as armature winding . and the other winding will be called a field winding. Let me explain How?
In case of D.c machines, we say that field winding is present on the stator field part and armature on the rotor. And we also know that brushes and slip rings are provided on the rotor which retrieves the emf induced in armature because of field windings. So where from you took the output? Rotor, No? So In case of D.C machines, we say the armature winding is present on the rotor.
In case of A.c machines, we have a concept of the stationary armature. As A.C machines have to generate a large amount of voltages so more winding are required and hence we put the windings through which we take output on the stator. So the output is taken out from the stator part as you can see in the figure below. Hence we can say armature winding is the one which is present on the Stator of A.c machines.
The above pic shows the three terminals (output) of the A.c generator.
My answer is to make it easy to remember which is armature and what is field winding when you see an electrical machine in front of you.