This definition clears up it up nicely for me: "In signal processing, sampling is the reduction of a continuous-time signal to a discrete-time signal... A samp

This definition clears up it up nicely for me: "In signal processing, sampling is the reduction of a continuous-time signal to a discrete-time signal... A sample is a value of the signal at a point in time and/or space; this definition differs from the usage in statistics, which refers to a set of such values." So it's a sample in the sense a set of (x, y, z, w) values from discrete timesteps represents a continuous timestep, but doesn't require specifying and using random variables to determine those timesteps.