Where does “asȳlum” come from?

asȳlum (Latin) comes from Ancient Greek ἄσυλον, from Ancient Greek ἄσυλος, from Ancient Greek ἀ-, from Proto-Hellenic hə-, from Proto-Indo-European sm̥-, from Proto-Indo-European sem- — together, one.

asȳlum (Latin): asylum (place of refuge), sanctuary