What is another word for shows once and for all?
Pronunciation: [ʃˈə͡ʊz wˈɒns and fɔːɹ ˈɔːl] (IPA) 
When you need to prove a point decisively, there are plenty of synonyms for the phrase "shows once and for all". You can use "demonstrates conclusively", "provides irrefutable evidence", or "settles the matter definitively". Other options include "confirms beyond doubt", "establishes once and for all", and "puts the issue to rest once and for all". You can also use idiomatic expressions, such as "nails it shut" or "puts the final nail in the coffin". Whatever phrase you choose, the goal is to convey finality and indisputability, leaving no room for doubt or debate.
