Nonsense is a communication, via speech, writing, or any other symbolic system, that lacks any coherent meaning. Sometimes in ordinary usage, nonsense is synonymous with absurdity or the ridiculous. Many poets, novelists and songwriters have used nonsense in their works, often creating entire works using it for reasons ranging from pure comic amusement or satire, to illustrating a point about language or reasoning. In the philosophy of language and philosophy of science, nonsense is distinguished from sense or meaningfulness, and attempts have been made to come up with a coherent and consistent method of distinguishing sense from nonsense. It is also an important field of study in cryptography regarding separating a signal from noise.
http://en.wikipedia.org/wiki/Nonsense
Nonsense can exist in reality as much as it can exist in the human mind. In such a case, confusion of the mind may result. In engineering, a signal may be distinguished from a noise by its content or substance and coherence. Both signal and noise exist in reality. These things are real. The task of the mind is to make sense of reality at hand. If it fails to do so then it perceives the reality of the signal as nonsense. However, the nonsense may only be perceived and therefore within one's mind as opposed to existing apart from it. One who speaks without a trace of sense may be defined as nonsense.
http://en.wikipedia.org/wiki/Nonsense
Nonsense can exist in reality as much as it can exist in the human mind. In such a case, confusion of the mind may result. In engineering, a signal may be distinguished from a noise by its content or substance and coherence. Both signal and noise exist in reality. These things are real. The task of the mind is to make sense of reality at hand. If it fails to do so then it perceives the reality of the signal as nonsense. However, the nonsense may only be perceived and therefore within one's mind as opposed to existing apart from it. One who speaks without a trace of sense may be defined as nonsense.