Where does “-āˀtas” come from?

-āˀtas (Proto-Balto-Slavic) comes from Proto-Indo-European -eh₂tos, from Proto-Indo-European -tós — Creates verbal adjectives from verb stems.

Ancestry of “-āˀtas”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	-eh₂tos	Forms adjectives from nouns, indicating the...
2	Proto-Indo-European	-tós	Creates verbal adjectives from verb stems

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