Question

what do you mean by amplitude​

Answer 1

Amplitude is an important parameter of waves and is the maximum displacement of points on a wave. 
or

the greatest distance that a wave, especially a sound or radio wave, moves up and down

Answer 2

Amplitude is directly proportional to square of loudness.
If amplitude increases,loudness increases by a factor of 4.
Amplitude is the maximum displacement of a of a bob from its mean position
...
Here,In the above pic,the displacement of the bob from A-B and B-C can b said as d amplitude of the vibrating body...
Hope ua ans..is clear mate...