Churchman's official list (5)
I believe the answer is:
canon
This might be a double definition.
'churchman's' is the first definition.
(I've seen this before)
'official list' is the second definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe they are linked in a way I don't understand?
Can you help me to learn more?
(Other definitions for canon that I've seen before include "Rule -- principle" , "accepted criterion" , "Standard" , "General principle or kind of clergyman" , "Senior clergyman" .)