'eastbound' originates from the combination of 'east' and 'bound', where 'east' refers to the cardinal direction and 'bound' means 'heading towards'.

'eastbound' evolved from the Old English word 'ēast' meaning 'east' and the Middle English 'bounden' meaning 'ready to go'.

Initially, it meant 'ready to go east', but over time it evolved into its current meaning of 'traveling or heading towards the east'.