Where does “χιλιοστό” come from?

χιλιοστό (Greek) comes from Greek χιλιοστός, from Ancient Greek χίλιοι, from Proto-Hellenic *kʰehliyoi, from Proto-Indo-European ǵʰéslom, from Proto-Indo-European sm̥-, from Proto-Indo-European sem- — together, one.

χιλιοστό (Greek): thousandth