English

interactinal

From inter- + actinal.

Proto-Indo-European *h₁én ‘in’

Proto-Indo-European *h₁entér ‘between’

Proto-Italic *n̥ter ‘between’

Latin inter ‘between’

Ancient Greek ἀκτίς ‘ray’

Today it means

adj Between rays.

Language periods are conventional ranges, not dates for this word.

Etymograph / interactinal