You misunderstood; the arbitrariness I address is not in the term cloud, rather in your definition which tries to somehow bundle processes that surround your perception of an entity and the existence of the entity. I am not saying it is not a valid approach, but still it could be as nonsense as the nonsense you ascribe to the detailed approach. How individual droplets become clouds, the outsiders' definition and possibly the insiders' too could be a very illustrative example in the discussion about societies etc.