A better rebuttal (5)
I believe the answer is:
worse
This could be a double definition.
'a better' is the first definition.
(thesaurus)
'rebuttal' is the second definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
Can you help me to learn more?
(Other definitions for worse that I've seen before include "Less satisfactory" , "More severe; less well" , "Of poorer quality" , "Opposite of better" , "Less good" .)