Where does “Rex” come from?

Rex (Cebuano) comes from English Rex, from Latin rēx, from Proto-Italic rēks, from Proto-Indo-European h₃rḗǵs, from Proto-Indo-European h₃reǵ- — to straighten, to right oneself; right; just.

Ancestry of “Rex”, step by step

StepLanguageWordMeaning
1EnglishRexroy
2Latinrēxking, ruler
3Proto-Italicrēksking
4Proto-Indo-Europeanh₃rḗǵsking, ruler
5Proto-Indo-Europeanh₃reǵ-to straighten, to right oneself; right; just
Every word from Proto-Indo-European h₃reǵ- →Every word from Proto-Indo-European h₃rḗǵs →Every word from Proto-Italic rēks →