This paper discusses the instability process in synthetic jets and how they transitioned into turbulent continuous flow. Axisymmetric synthetic jet was investigated and the results were compared against conventional turbulent jet and previous studies for synthetic jet. Time resolved PIV data was used to obtain velocity and frequency information of the flow. It was shown that the transition process occur due to vortex merging at x/D =5.5 and x/D = 7. These locations correspond to the location where the energy in the subharmonic frequency is at max. The forcing frequency of the jet dominates the flow characteristics of the synthetic jet, but using the triple decomposition method it was shown that the random fluctuations in the jet are similar to the continuous jet. The rise of the random fluctuations and the fall of the deterministic fluctuations are directly related to the transition process of the jet. Nomenclatures