I will say loneliness is characteristic of ‘alone’, a league and class of its own which has nothing similar. All existing beings and objects are of substance, so they should not be referred to as alone? For me, therefore, it has been wrongly associated with humans, as they are never alone (surrounded by thoughts, memories, or physical beings and objects). In other words, all living and non living beings and things are not alone and therefore cannot experience lonliness. The question remains unanswered…to answer look at the definition of 'alone', which is “Of or by itself; without any thing more or any one else. Close example using existing limited dictionary vocabulary can be – Nothingness or Vacuum, just as sound can have many shades…so it will never be alone, silence will always be! The only reason which may be attributed to using it for humans is metaphorically not realistically – to ‘stress’ the person is by her/himself…