A word of questionable value (13)
I believe the answer is:
interrogative
This could be a double definition.
'a word' is the first definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'questionable value' is the second definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'of' is the link.
Can you help me to learn more?
(Other definitions for interrogative that I've seen before include "raising questions" , "Denoting a question" , "Questioning" .)