Fundamental reason for full stop? (5)
I believe the answer is:
point
I believe this is a triple definition!
'fundamental' is the first definition.
(thesaurus)
'reason' is the second definition.
(thesaurus)
'for full stop?' is the third definition.
(synonyms)
(Other definitions for point that I've seen before include "Bearing - precise moment" , "... indicate location" , "Indicate - off-side fielding position" , "meaning" , "The whole idea" .)