syn·chro·nous 
(sĭngkrə-nəs, sĭn-)
(sĭngkrə-nəs, sĭn-)adj.
1. Occurring or existing at the same time. See Synonyms at contemporary.
2. Moving or operating at the same rate: synchronous motors.
3.
a. Having identical periods.
b. Having identical period and phase: synchronous oscillations.
c. Relating to or being a satellite that orbits a celestial body at a speed that matches the body's rotation, thus remaining stationary as observed from the body's surface.
d. Synchronized by an electronic clock: synchronous signaling.
[From Late Latin synchronus, from Greek sunkhronos : sun-, syn- + khronos, time.]
synchro·nous·ly adv.
synchro·nous·ness n.