Most of the message can have variations (6)
I believe the answer is:
themes
'have variations' is the definition.
The answer and definition can be both related to communication as well as being plural nouns.
Maybe they are linked in a way I don't understand?
'most of the message' is the wordplay.
'most of' means to remove the last letter.
'message' becomes 'emes' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'the' with its last letter taken away is 'th'.
'th'+'emes'='THEMES'
'can' acts as a link.
Can you help me to learn more?
(Other definitions for themes that I've seen before include "Subjects or unifying ideas" , "Subjects or repeated musical pieces" , "Motifs, subjects" , "Subjects or repeated melodies" , "Topics, ideas, motifs" .)