Pyrotechnical tosh (3)

I believe the answer is:
rot
'tosh' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'pyrotechnical' is the wordplay.
'ROT' is hidden in amongst the letters.
However, I am unsure how this is indicated.
Can you help me to learn more?
(Other definitions for rot that I've seen before include "Corruption" , "Decay - nonsense" , "Deterioration" , "Paradise" , "Drivel" .)
