Fluid antenna system (FAS), enabled by dynamic, software-defined antenna architectures, introduces a new degree of freedom (DoF) to enhance wireless communications performance. In this letter, we consider a point-to-point system where a transmitter equipped with multiple fixed antennas communicates to a mobile receiver equipped with a FAS. We investigate the outage probability performance of this system. Our analysis is based on a copula approach, which can model the correlation between the channels at different ports of FAS and permits the evaluation of the outage probability via the copula. Both student- ${t}$ and Gaussian copulas are considered. Our numerical results demonstrate that the size of FAS has a greater impact on the achievable performance than its resolution.