There are many words that end with the letter x such as borax, apex, fix, sphinx, fox, crux and onyx. However, there are no words that end with the letter RX.
meninx singular of meninges
syntax
Onyx
Windex
Ajaxflaxcoaxhoaxflexplexapex.
Jinx
xerographically
xerographically
jinx
Xerox
Xi