Excellent base (4)
I believe the answer is:
mean
I believe this is a double definition.
'excellent' is the first definition.
(thesaurus)
'base' is the second definition.
(synonyms)
(Other definitions for mean that I've seen before include "spell" , "Intend - average - poor" , "Mid-point" , "Intend - miserly" , "Type of average" .)