Where does “Ostsee” come from?

Ostsee (German) comes from German Ost, from Middle High German ōst, from Old High German ōst, from Old Norse austr, from Proto-Germanic austrą, from Proto-Germanic austraz, from Proto-Indo-European *h₂éwsteros — in the direction of dawn, east.

Ancestry of “Ostsee”, step by step

Ostsee traces back through two separate lines of ancestry.

via German Ost

StepLanguageWordMeaning
1GermanOstthe east; a wind coming from the east
2Middle High Germanōst
3Old High Germanōsteast
4Old Norseaustreast
5Proto-Germanicaustrąeast; east, eastward
6Proto-Germanicaustrazeast, eastern
7Proto-Indo-European*h₂éwsterosin the direction of dawn, east

via German See

StepLanguageWordMeaning
1GermanSeelake; sea, ocean; sea, sea condition, swell
2Old High Germansēosea
3Proto-West Germanicsaiwisea
4Proto-Germanicsaiwizsea, ocean
5Proto-Germanicsīhwanąto filter
6Proto-Indo-Europeanseykʷ-to moisten; to filter
7Proto-Indo-Europeansey-to be wet; dribble; run; to stretch one's arm;...
Every word from Proto-Indo-European *h₂éwsterosEvery word from Proto-Germanic austrazEvery word from Proto-Germanic austrą