Where does “alo-” come from?

alo- (Italian) comes from Ancient Greek ἅλς, from Ancient Greek -ῐος, from Proto-Indo-European -yós — Creates adjectives from noun or verb stems.

alo- (Italian): halo-

Definitions

Step	Language	Word	Meaning
1	Ancient Greek	ἅλς	salt; brine; sea
2	Ancient Greek	-ῐος	belonging to; of”, “belonging to”, “pertaining to
3	Proto-Indo-European	-yós	Creates adjectives from noun or verb stems

alo- — Etymology, Origin & Word History | Etymology Explorer