Learn how to say Synchronous correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word synchronous:
occurring at the same time; contemporaneous
(physics) (of periodic phenomena, such as voltages) having the same frequency and phase
occurring or recurring exactly together and at the same rate ⇒ the synchronous flapping of a bird’s wings
C17: from Late Latin synchronus, from Greek sunkhronos, from syn- + khronos time