Loosely defined, nonsense includes everything plainly at variance with obvious fact. Efforts may however be made to distinguish fairly sharply between the false and the nonsensical, although there may be no agreement as to where the line should be drawn. Distinctions may be made between: (a) nonsense as obvious falsehood (when contrary to the observed facts); (b) semantic nonsense (when information is provided out of context and without any attempt to relate it to the context in which it is assessed); (c) deviant utterances involving mixing of categories such that some of the communication is meaningful and the rest nonsense; (d) jumbled strings of familiar words lacking any familiar syntax; (e) vocabulary nonsense in which the syntax is meaningful but for which the words used are unfamiliar; (f) nonsense as gibberish in which there is neither familiar vocabulary nor familiar syntax.
Nonsense is frequently perceived as characterizing the communications of opponents, especially those favouring alternative policies and notably in parliamentary debate. Utterances may be considered nonsensical in a given language at a given time if the majority of the population balks at it, although it is necessary to accept that some may not balk at it and that many, in the future, will find it quite meaningful. Nonsense is both a widespread byproduct of human communication and a professional danger for philosophers, especially those with metaphysical orientations.
Claimed as a distinctive ability of man: "the privilege of absurdity to which living creature is subject, but man only. And of men, those are of all most subject to it that profess philosophy" (Thomas Hobbes).