Where does “ความชอบธรรม” come from?

ความชอบธรรม (Thai) comes from Thai ชอบธรรม, from Thai ธรรม, from Sanskrit धर्म, from Proto-Indo-Iranian dʰármas, from Proto-Indo-European dʰer- — to support; to hold.

Ancestry of “ความชอบธรรม”, step by step

ความชอบธรรม traces back through two separate lines of ancestry.

via Thai ชอบธรรม

StepLanguageWordMeaning
1Thaiชอบธรรมlegitimate; lawful; legal; statutory
2Thaiธรรมdharma; doctrine
3Sanskritधर्मmorality, virtue, moral code, good deed, good...
4Proto-Indo-Iraniandʰármas—
5Proto-Indo-Europeandʰer-to support; to hold

via Thai ความ

StepLanguageWordMeaning
1Thaiความaffair; matter; content; essence; subject;...
2Proto-Taiɣwaːmᴬmatter
Every word from Proto-Indo-European dʰer- →Every word from Proto-Indo-Iranian dʰármas →Every word from Sanskrit धर्म →