Eastbound means travelling towards where the sun rises. The eastbound platform, an eastbound flight, eastbound traffic.
Eastbound flights across the Atlantic are shorter because the jet stream pushes them, sometimes by an hour or more. Jet lag is worse going east, because the body finds it harder to shorten a day than to lengthen one. Note westbound, its opposite.
1adjectiveeastboundTravelling towards the east.
“The eastbound train to London leaves from platform two.”
eastbound is a direction of travel.
Middle English
est
English
east
English, today
eastbound
From east + -bound. east comes from Middle English est. From Middle English est, from Old English ēast, from Proto-West Germanic austr, from Proto-Germanic austrą, from Proto-Germanic austraz, from Proto-Indo-European h₂éwsteros (“east”). 2
Etymology from Wiktionary, CC BY-SA