Where does “πεντηκόντορος” come from?

πεντηκόντορος (Ancient Greek) comes from Ancient Greek πεντήκοντα, from Proto-Indo-European penkʷēḱomth₂, from Proto-Indo-European *pénkʷedḱomt.

Ancestry of “πεντηκόντορος”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	πεντήκοντα	fifty
2	Proto-Indo-European	penkʷēḱomth₂	—
3	Proto-Indo-European	*pénkʷedḱomt	—

πεντηκόντορος — Etymology, Origin & Word History | Etymology Explorer