Eastern means belonging to the side where the sun comes up. Eastern Europe, the eastern shore, an eastern wind.
Capitalised it names political and cultural regions rather than directions, and those move — Eastern Europe meant something quite different before 1989. Note the -ern ending shared by all four directions, and that an eastern wind blows from the east, not towards it.
1adjectiveeasternBelonging to the east.
“The storm is moving towards the eastern coast of the island.”
eastern is a direction.
Old English easterne comes from east, from a root meaning dawn. Easter shares the root.
Proto-Indo-European
*h₂ews-ro- — eastern
Proto-Germanic
*austrōnijaz — eastern
Old English
ēasterne — eastern
Middle English
esturne
English, today
eastern
From Middle English esturne, esterne, from Old English ēasterne (“eastern”), from Proto-Germanic austrōnijaz (“eastern”), from Proto-Indo-European h₂ews-ro- (“eastern”), from Proto-Indo-European h₂ews- (“dawn, east”). Cognate with Old Saxon - and Old High German ōstrōni (“eastern”), Old Norse austrœnn (“eastern”). Morphologically east + -ern.
Etymology from Wiktionary, CC BY-SA