synchronous

Concise Oxford English Dictionary © 2008 Oxford University Press:
synchronous /ˈsɪŋkrənəs/

▶adjective

• 1 existing or occurring at the same time.

• 2 of or denoting a satellite which revolves in its orbit in exactly the same time as the primary body rotates on its axis.

– derivatives
synchronously adverb.

– origin C17: from late L. synchronus (from Gk sunkhronos, from sun- ‘together’ + khronos ‘time’) + -ous.