Terrain

Terrain Is perceived

 ‘flat’ by some;

 ‘steep’ by some;

 ‘quick sand’ by some;

‘rocky’ by some;

‘river’ by some;

 ‘tunnel’ by some; 

‘forest’ by some;

 ‘desert’ by some;

‘bridge’ by some;

‘cave’ by some;

‘wall’ by some;

‘cliff’ by some;

‘pit’ by some;

Therefore, what is a terrain??....