Where does “ثابت” come from?

ثابت (Classical Persian) comes from Arabic ثَابِت, from Arabic ثَبَتَ — to be firm, to be fixed; to be firm, to persist;...

Ancestry of “ثابت”, step by step

Step	Language	Word	Meaning
1	Arabic	ثَابِت	constant; stable; unchanging; certain; permanent
2	Arabic	ثَبَتَ	to be firm, to be fixed; to be firm, to persist;...