synchronous

The story

1. Ancient Greek · derived fromσύγχρονος“contemporaneous”
2. Late Latin · borrowed fromsynchronus
3. English todaysynchronous

Borrowed from Late Latin synchronus, from Ancient Greek σύγχρονος (súnkhronos, “contemporaneous”), from σῠν- (sŭn-, “with, together”) + χρόνος (khrónos, “time”). By surface analysis, syn- + chron- + -ous = synchrony + -ous; however, all related words (e.g., synchronic, synchrony, synchronicity, diachronous, diachronic, diachrony, diachronicity) were coined later, either as back-formations from, or otherwise by analogy with the surface analysis of, synchronous.