Where does “tartarus” come from?

tartarus (Latin) comes from Ancient Greek Τάρταρος, from Ancient Greek Ταρτησσός, from Ancient Greek Ἡράκλειοι Στῆλαι.

Ancestry of “tartarus”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	Τάρταρος	Tartarus
2	Ancient Greek	Ταρτησσός	—
3	Ancient Greek	Ἡράκλειοι Στῆλαι	—