Where does “अधमर्णिक” come from?

अधमर्णिक (Sanskrit) comes from Sanskrit अधम, from Proto-Indo-Iranian *(H)adʰamás — lowest.

Ancestry of “अधमर्णिक”, step by step

अधमर्णिक traces back through two separate lines of ancestry.

via Sanskrit अधम

StepLanguageWordMeaning
1Sanskritअधमlowest, very low
2Proto-Indo-Iranian*(H)adʰamáslowest

via Sanskrit ऋणिक

StepLanguageWordMeaning
1Sanskritऋणिक—
Every word from Proto-Indo-Iranian *(H)adʰamás →Every word from Sanskrit अधम →