Hi,
The online dictionary from Naver.co.kr had this definition of 'diminution':
N-UNCOUNT : usu N of/in n
A diminution of something is its reduction in size, importance, or intensity.[ FORMAL ]
despite a slight diminution in asset value.
reduction
Why the definition has the article 'A' in its definition and its example phrase when it is noted as an uncountable noun, which a notation that seems to indicate the usually occuring position of Noun of noun or Noun in noun?
I don't see it as uncountable, although it most often used in the singular. I see it as one of those words that can be used in both a count way (there were many diminutions in the value of his assets in the last 10 years) and a non-count way (I saw some diminution in the amount of flood-water yesterday).
Best wishes, Clive