Definify.com
Webster 1913 Edition
Subject-matter
Sub′ject-matˊter
,Noun.
 The matter or thought presented for consideration in some statement or discussion; that which is made the object of thought or study. 
As to the 
subject-matter
, words are always to be understood as having a regard thereto. Blackstone.
As science makes progress in any 
subject-matter
, poetry recedes from it. J. H. Newman.